‘\¢*, Marine Fisheries Se REVIEW “ Stares oF ad National Oceanic and Atmospheric Administration * National Marine Fisheries Service The Walleye Pollock Marine Fisheries On the cover: The walleye pollock, Theragra chalcogramma. 56(1), 1994 Articles The Origins of New Zealand’s Chinook Salmon, Oncorhynchus tshawytscha Robert M. McDowall Survey Assessment of Semi-pelagic Gadoids: The Example of Walleye Pollock, Theragra chaicogramma, in the Eastern Bering Sea William A. Karp and Gary E. Walters Fisheries Management: The Kuwaiti Experience C. P. Mathews Trade and Management: Exclusive Economic Zones and the Changing Japanese Surimi Market John T. Sproul and Lewis E. 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L. Hobart law of this Department. Use of the funds for printing Government Printing Office, Washington, DC 20402. The Origins of New Zealand’s Chinook Salmon, Oncorhynchus tshawytscha ROBERT M. McDOWALL Introduction Russia, spread further into Scandinavia, parison, the New Zealand situation is but were only briefly successful there quite unequivocal and of long-standing New Zealand’s acclimatized stocks (Berg, 1977; Bakshtansky, 1980). clarity: Chinook salmon have been es- of anadromous chinook salmon, Oncor- Transplants of various species of tablished as self—supporting, anadro- hynchus tshawytscha, are one of very Oncorhynchus to Chile generated some mous populations, primarily in rivers few unequivocally successful trans- adult returns from smolts released to along the east coast of New Zealand’s plants of any anadromous Pacific sea, though these do not seem to have South Island, since about 1905 salmon, and the only one of long stand- persisted (Zamorano, 1991). By com- (McDowall, 1990; Fig. 1). ing (Childerhose and Trim, 1979). This lack of success is in spite of attempts to establish various salmon species in many areas, that date back to the era when salmonids were being shipped to many and diverse parts of the world prior to about the 1930's, including such unlikely places as Brazil, Hawaii, Mexico, and Nicaragua (McDowall, 1988). Early attempts to establish anadromous pink and coho salmon, O. gorbuscha and O. kisutch, respectively, Occasional fish stray into diverse in northeastern North America seem North Island rivers ultimately to have failed, despite initial signs of success (Lear, 1980). Pink salmon, transplanted to western Arctic Robert M. McDowall is with the National Insti- tute of Water and Atmospheric Research, P.O. Box 8602, Christchurch, New Zealand. Minor and _ erratic runs in some west coast rivers » ABSTRACT—Chinook salmon, Oncor- & hynchus tshawytscha, are well established as anadromous and landlocked runs in New Zealand. Ova introductions during the 1870's (probably from the McCloud River, California, U.S.A.), failed to generate Major runs into anadromous stocks, but further introduc- east coast rivers tions of fall-run salmon ova from hatcher- ies in California’s Sacramento River basin Waitaki River in the early 1900’s were successful and formed the basis for existing runs. The first batch of ova in the 1900’s consignments originated from Battle Creek, a Sacramento River tributary, but the explicit source of later batches is not known. It seems likely that the successful runs stem from the sec- Figure 1. — Distribution of anadromous chinook salmon in New ond batch (1903 brood year—1904 consign- Zealand, showing broad presence along the east coast of the South ment in New Zealand), probably augmented Island, intermittent and minor runs on the west coast, and occa- by returns from later importations. sional stragglers appearing more widely throughout New Zealand. 56(1), 1994 New Zealand is widely known for its and Leary, 1988; Behnke, 1992; ies in the upper river, including Mill stocks of acclimatized salmonids, espe- Hilborn, 1992). Creek, the McCloud River, and other cially of brown trout, Salmo trutta, and “Wild” trout and salmon have be- waters where chinook salmon stocks rainbow trout, O. mykiss; less well come something of a “clarion call” spawned (Cope and Slater, 1957). These known are its acclimatized stocks of among those sensitized to the issue of were waters where racks and hatcher- Atlantic salmon, Salmo salar; brook protecting local stocks (White, 1992). ies had operated in earlier years to pro- char, Salvelinus fontinalis; lake trout, S. This same concern is relevant to New vide salmon ova for release in many namaycush; and sockeye salmon, O. Zealand’s stocks of chinook. For many other areas, including New Zealand. nerka (McDowall, 1990). The origins decades after their early 1900’s estab- Early New Zealand of stocks of these species have been of lishment they were not interfered with, Chinook Salmon Introductions considerable interest and confusion— and hatchery releases into the rivers interest stimulated by a concern to un- were minimal; however, with the devel- Initial introductions of chinook derstand the stock origins of the popu- opment of enhancement technologies in saimon to New Zealand took place in lations, and confusion generated by western North America and the prospect the 1870’s. In 1875 the Hawkes Bay poor record keeping when the fish were of ocean ranching both for commercial Acclimatisation Society obtained ova transported around the globe between purposes and to enhance recreational “through Dr. Spencer F. Baird, Chair- the 1860’s and early 1900’s. The ori- angling in New Zealand, extensive man of the United States Fishery Com- gins of New Zealand’s rainbow trout hatchery releases and transfers between mission” (Thomson, 1922). The ova, were clarified by Scott et al. (1978) and catchments were undertaken during the though originally destined for the town of the sockeye by Hardy (1983) and 1970’s and 1980’s (McDowall, 1990). of Napier, began to hatch as they Scott (1984). However, the source of The concerns that apply to stocks in reached Auckland, and they were re- New Zealand’s chinook salmon has not North America therefore have similar leased into nearby rivers; none reached been reviewed since the fish were es- implications for the management of Napier. Further consignments were sent tablished in New Zealand in the early New Zealand’s acclimatized chinook in 1876, 1877, and 1878, but contem- 1900’s, and their explicit source remains stocks. Even though these have not had porary New Zealand accounts do not a matter for speculation. millions of years of local selection to state their explicit origins; the common Questions relating to genetic and phe- adapt them to the different conditions assumption has been that they came notypic differences among stocks of found in New Zealand rivers (as is true from the Baird Hatchery on California’s Pacific coast salmonids have generated in North America), there is nevertheless McCloud River, a tributary of the much research interest in recent years. evidence to suggest that fundamental Sacramento. This is due partly to extensive hatchery life history parameters such as age and A history of California salmon hatch- releases, made either for enhancement size at maturity, spawning season, and eries suggests that, at this early period, or regeneration of heavily exploited relative fecundity, differ among New the Baird Hatchery was the only one in anadromous salmonid runs, or to restore Zealand river systems (Quinn and a position to provide ova for New those damaged by habitat deterioration Unwin, 1993). Zealand (Leitritz, 1970). Their source and river impoundment. There have also Among certain stocks at risk in North is largely of academic interest, anyway. been widespread and massive releases America have been the diverse chinook There is only slim evidence that even to support recreational salmonid fish- salmon stocks of the Pacific coast an occasional salmon from the 187(C’s eries. In addition, there has been active (McDonald, 1981; Nehlsen et al., releases may have returned to New interest in the evolution of Pacific 1991); because of the fragility of some Zealand rivers as adults, e.g. a few salmon species and stocks. of these stocks, the presence of accli- rather modest-sized fish, thought by Considerable concern has grown matized chinook salmon in New some to be chinook salmon, were taken about these various hatchery releases. Zealand is of wider interest and their from rivers like the Waimakariri (3.6, Often the fish are of different (and even stock origins in North America of par- 2.4, and 2.0 kg) and Waitaki (4.4 kg; unknown) genetic provenance from ticular interest. In addition, the presence Thomson, 1922), but there is as much those already present in the receiving of these stocks in New Zealand for likelihood that they were sea—run brown ecosystems, and sometimes they are of about 90 years provides a valuable op- trout which abounded in such rivers and reduced genetic diversity as a result of portunity to examine changes in allele grew to this or greater size. many generations of hatchery rearing. frequencies during that period of isola- One early report claimed that a fish There is legitimate concern that these tion. For this reason alone, identifica- from a New Zealand river (1884) was hatchery introductions might disrupt tion of the origins of New Zealand identified as a California salmon by T. fish stocks finely adapted to local habi- chinook stocks would be of interest. In H. Bean, of the U.S. National Museum tat characteristics; there is concern to particular, the stocks on the Sacramento (N.Z. Marine Department, 1885) Unfor- protect the genetic integrity of locally River (Rutter, 1902) suffered severely tunately, this fish is no longer in the adapted stocks, sometimes recognized from the construction of the Shasta Dam collections of the Museum. Thomson as local subspecies of more widely dis- in 1943, which prevented salmon from (1922) related several events reputed to tributed polytypic species (Allendorf reaching the many spawning tributar- involve specimens of Oncorhynchus Marine Fisheries Review from New Zealand rivers. L. F. Ayson, clearly thought that these 1870’s intro- fish northwards, and help to establish who was responsible for the later, suc- ductions were probably a failure. runs in other South Island rivers north cessful introductions of chinook Ayson visited North America in 1899 of the Waitaki. And so it soon proved. salmon, and who was New Zealand’s and returned with offers of salmon ova, Records of Early Chief Inspector of Fisheries from 1898, noting that supplies could be obtained 1900’s Importations wrote that “apparently some fish caught from the Baird and Battle Creek Hatch- in the Waitaki River have been identi- eries and Canada’s Fraser River; from New Zealand records of how many fied as belonging to the Pacific Salmons his detailed description, it is clear that consignments of chinook came to New or Oncorhynchus family,” but he he visited Battle Creek, but apparently Zealand are inconsistent, some listing thought the evidence “far from compel- not Baird Hatchery (N.Z. Marine De- four, others five. The New Zealand ling” (N.Z. Marine Department, 1899). partment, 1899). When he returned to Marine Department, the agency respon- Whether or not any of these fish were New Zealand, Ayson recommended that sible for the importations (1901-07), chinook remains uncertain, and in terms the American offer should be accepted, recorded that five consignments of of the present stocks of chinook salmon and he successfully promoted further chinook salmon ova were shipped, the in New Zealand it is probably unimpor- major and repeated importations of Pa- available details being as follows (North tant. What is very clear is that if chinook cific salmon ova. The New Zealand American brood years are the previous were still present in New Zealand by Government approved construction of year in all instances): 1900, as a result of the 1870’s importa- a hatchery on the Hakataramea River, a tions, they were sparse indeed. Such tributary of the Waitaki (Fig. 2). 1) 1901-—500,000 ova, arrived in New runs, if any, were most likely restricted The 1870’s consignments of salmon Zealand in early January; to rivers of Canterbury where stocks of ova to New Zealand, which were of 2) 1904~-300,000 ova, arrived in January; chinook are now present, since there spring—run stock (those that enter riv- accompanied by G. H. Lambson; were never even hints of consistent runs ers from the sea during spring), had 3) 1905—300,000 ova, arrival date not in any other New Zealand rivers before been liberated in small batches in many given; accompanied by L. F. Ayson; 1900, nor have there been since, apart rivers. Ayson was critical of this prac- 4) 1906—500,000 ova, arrival date not from some sparse and intermittent runs tice and intended concentrating the given; accompanied by L.F. Ayson; on the South Island’s west coast (Fig. forthcoming releases on one river sys- 5) 1907-—500,000 ova, left the United 1). There were certainly no fish running tem. He chose the Waitaki River partly States 8 February, arrived in New into any of these rivers in the late 1800’s because of its resemblance to western Zealand late February; accompanied in numbers comparable with those that North American salmon rivers—and he by L. F. Ayson (N.Z. Marine Depart- followed the early 1900’s releases, and knew the Waitaki well, having worked ment, 1901-08) it can be concluded that even if there there earlier in his life. It was also partly were a few salmon in these rivers, their because he surmised that north—flow- These Marine Department records genetic contribution to the stocks that ing ocean currents sweeping past the are consistent with data on ova handled developed rapidly in the early 1900’s Waitaki River mouth would disperse the by California hatcheries of the U.S. Fish was probably minor. Most commentators have considered the 1870’s releases a failure. Certainly, the attitude of L. F Ayson, who had major involvement in the early 1900’s chinook releases, gave no support for any significant success following the 1870’s releases. He obviously saw some glimmers of success in 1899, but he also proposed a series of further major im- portations, and probably would not have done so had he thought there were sig- nificant existing runs. Somewhat later he was even more definite and negative, thinking that “had any of these prolific fish survived from the spasmodic efforts to acclimatize them previous to 1900, they would have disclosed themselves long before the . . . importations in 1900” (N.Z. Marine Department, 1917). Thus, Ayson, on the basis of his con- Figure 2. — The Hakataramea hatchery (probably ca. 1920’s), built in the early 1900’s to temporary knowledge and experience, support the chinook salmon introduction program; it remained in operation until 1942. 56(1), 1994 Commission for the brood years 1900— details of the source of ova were pub- and at the Government’s Hakataramea 06 (U.S. Commission of Fish and Fish- lished by the Commission, and records Hatchery, eventually assuming control eries, 1902, 1903; U.S. Bureau of Fish- of ova shipped from the Baird Station of it. He may have been familiar with eries, 1904-07); Ayson (1910), in his were largely lost in a fire at Baird in this early history. In a report evidently slightly later review, also listed five con- 1909. Consequently, there are appar- written in 1958, Charles Ayson (1959) signments. However, Thomson (1922), ently no surviving details of the explicit asserted that the first fish to come back in his very detailed, and usually authori- source of the four later New Zealand from the sea weighed 5.5 kg and was tative, historical account of animal in- consignments, though they are likely to taken in the Hakataramea trap in May troductions to New Zealand, listed only have come from the various hatcheries 1905. At this time it would have been four batches, omitting that which arrived in the Sacramento River basin. 4.5 years old, if derived from the origi- in New Zealand in 1905; this account has nal 1901 release. However, dating this Returns From the wide acceptance. Perhaps coincidentally, return was Clearly controversial at the Early 1900’s Releases noted U.S. ichthyologist Charles Gilbert, time, as Ayson (1959) added that: “Dif- ina letter! to C. A. Vogelsang of the Cali- The first indication of the return of ferent dates have been given ... as to fornia Department of Fish and Game (12 chinook salmon to New Zealand waters the year of the first returned fish, but March 1910) also wrote of just four con- from the early 20th century releases was ... 1905 is definitely correct.” This signments. It appears that both Thomson a report that “fish believed to be salmon 1959 account of events in 1905 differs and Gilbert were wrong. have been caught at the mouth of the from others, including some that were No totally contemporary publications Waitaki River” (N.Z. Marine Depart- much more contemporary (N.Z. Marine in New Zealand state where any of these ment, 1905). In a report dated 9 Decem- Department, 1906; Ayson, 1910; ova came from, apart from “United ber 1905, James Hector, a noted New Thomson, 1922). Further, in the same States”; however, Ayson (1910) shortly Zealand naturalist, reported that a fish 1959 report Ayson stated that in the thereafter stated that the 1901 ova “were sent to him was “without doubt a young early 1900’s “probably five million supplied by the United States Bureau specimen of the genus Oncorhynchus” salmon eggs were imported,” and this of Fisheries, from its station at Baird, (N.Z. Marine Department, 1905), but it figure, too differs greatly from other California, on the McCloud River [and] is not possible to determine from reports (mostly 2.1 million ova, though came over in charge of Mr G. H. Hector’s account whether this fish was Davidson and Hutchings (1938) re- Lambson, superintendent of the Baird from a return in the “1905” run or a very ported 1.6 million). This discrepancy casts Station.” However, the latter source was early return from the “1906” run; either further doubt on the accuracy of Charles not recorded in the initial account of the is possible. Ayson’s account, which seems to be based importation (N.Z. Marine Department, It is probably not important. The fish entirely on memory, and was written 50 1901), an account which Ayson, him- itself, which Hector thought a “young years after the event by an elderly man. self, probably wrote. specimen,” was only 522 mm long, and L. F. Ayson reported numerous fish Ayson’s (1910) statement that the of particular note had “rudimentary tes- caught by anglers during the 1906 sea- 1901 batch came from Baird Hatchery tes.” Since 448 4-year-old chinook son (N.Z. Marine Department, 1907), is not as unambiguous as it seems, be- salmon had been reared at and released and Hector was again sent specimens cause ova were often shifted between from the Hakataramea hatchery during for study. One was a ripe female of 7.3 the hatcheries on tributaries of the Sac- 1904-05 (Thomson, 1922), the fish kg, and then three more fish, a male 635 ramento River (Baird, Battle Creek, Hector examined was probably one of mm and 2.7 kg (spent), a female 559 Mill Creek, etc.). In this regard, records these. Fish of this small size with rudi- mm and 2 kg (spent), and a male 432 of 1900 brood year ova handled by mentary testes certainly do not feature mm and 0.7 kg (ripe). Hector consid- Battle Creek are quite explicit, stating in the present chinook salmon runs in ered that the two larger of this trio of that “3,079,660 [ova] were transferred New Zealand rivers. Small “jacks” of fish were 4-year-olds and the smaller to the Sisson hatchery of the California this size are common enough in the one a 3-year-old; if these ages were cor- Commission and to Baird station, in- runs, but are sexually mature, typically rect, these fish were only a fraction of cluding 500,000 sent to New Zealand.” with well-developed testes. Given the the size of chinook salmon of these ages The 1901 consignment, thus definitely hatchery rearing of fish to 4 years old in modern runs in New Zealand (Flain, came originally from Battle Creek not before release, and the rudimentary state 1982; McDowall, 1990), and it implies Baird, and were from fall—run fish, as it of the testes of this fish, it may never that they, too, may have been hatchery— was found impossible to get summer run have been to sea. Nothing more conclu- reared for some time before release; chinook from Battle Creek, owing to its sive can be drawn from this report of they, too, may never have been to sea, high water temperatures at that season returns in 1905. Whether any truly sea— or have done so only briefly before re- (U.S. Commission of Fish and Fisher- run fish were caught in 1905 is not turning to the Waitaki River—scarcely ies, 1902). This is the last year in which known; any would have been from the evidence of the foundations of an 1901 consignment. anadromous salmon run. Charles Ayson, son of L. F. Ayson, The 7.3 kg fish therefore assumes ' Letter in possession of Mark R. Jennings, 1830 Sharon Ave., Davis, Calif. 95616. also worked on the Waitaki salmon run, greater significance. Judging by current Marine Fisheries Review growth rates of chinook in New Zealand Though it might seem that the pri- There is no hint of any salmon re- (Flain, 1982; Quinn and Unwin, 1993), mary question to discuss would be the turning in 1902, 1903, or 1904, so the a 7.3 kg fish would be either 3 or 4 years second of those listed above, identifi- likelihood of a return of fish from the old. This fish is therefore probably the cation of the source population depends 1901 release seems slim; an unobserved first captured chinook salmon that went on establishing which New Zealand re- run into a small river like the Haka- to sea and returned as a mature, leases produced the returns. taramea (3.5 m?/second median flow) prespawning adult. There were evi- As noted above, the key fish in all seems unlikely, with workers busy on dently others in the river that year, as this discussion appears to be the 7.3 kg the river rearing salmon at the hatchery there were newspaper reports of a few fish examined by Hector in June 1906 and with keen anticipation of a return salmon spawning in the Hakataramea since this was the first almost certainly of fish from earlier releases. With re- River at that time, April-May (fall—win- anadromous salmon known to have re- leases made from the production of a ter) 1906. turned, and was presumably represen- consignment of 500,000 ova, returns During 1907 there was a modest run tative of the first “run” from the early from this batch could have been pro- of salmon into the Waitaki. Though 1900’s introductions. This fish could lific. Although there will never be any most of the run was over before the riv- have been derived from the 1901 (1900 certainty, this fragmentary evidence ers were inspected, 30,000 ova were California brood year) importation, in leaves us with the probability that the obtained from fish in the 1907 run into which case it would have been about 5.5 first returns were from the 1904 release, the Hakataramea (N.Z. Marine Depart- years old. Or it could have been from and that this release, either alone, or ment, 1908), and Ayson (1910) wrote the 1904 (1903 brood year) importation, probably with augmentation from the later of “quite a run of salmon up the which would have made it about 2.5 1906 and 1907 releases, formed the Waitaki River [which] spawned in sev- years old. Ayson’s comment that the source of New Zealand’s chinook eral of its main tributary rivers. In the more abundant fish that returned in salmon runs. Because the origin of the Hakataramea between 300 and 400 1907 were larger may suggest that these 1904, 1906, and 1907 importations is salmon had spawned naturally in the 3 were from the same brood year as the not explicitly documented, all that can kilometres of river before it joins the 1906 return, but a year older, i.e. fish be said is that they came from the Sac- Waitaki.” A similar run was reported in that were “considerably heavier” than ramento River drainage system. 1908, though the fish were “on average 7.3 kg and either 6.5 or 3.5 years old. As L. F. Ayson (Fig. 3) recounted, . .. considerably heavier.” These events There is no way of being certain which initial returns to New Zealand rivers confirm the initiation of a run in 1906— of these ages is correct, but it seems took place in the autumn and early win- 07 of chinook salmon into the Waitaki probable, on the basis of the ages and ter, equating with a fall run of chinook that resulted from the 1901-07 releases, sizes of chinook salmon that now re- salmon in California. This return tim- and which became the progenitor of turn to New Zealand rivers (Flain, 1982; ing could have occurred because the runs into other rivers along the east Quinn and Unwin, 1993), and in the ap- parent stock in California were fall—run coast of New Zealand’s South Island. parent absence of runs into the Waitaki/ fish, or it could have been because the In a few years, salmon spread natu- Hakataramea Rivers in 1903, 1904, and fish were ready to return to fresh water rally north along the coast of the South 1905, that the lower age is correct-that after 2.5 or 3.5 years at sea, as they Island, just as L. F. Ayson had hoped, there was a small return of a few fish in would have been if they were spring— establishing anadromous runs in the 1906, probably including the 7.3 kg fish, run fish. If maturation in chinook Rangitata, Opihi, Ashburton, Rakaia, 2.5 years old, and from the 1904 release, salmon is triggered by changes in day Waimakariri, Hurunui, and Waiau Riv- rather than 5.5 years old and from the length, the former scenario is more ers; these runs persist today (McDow- 1901 release. If that is so, the more likely. all, 1990) (Fig. 1). abundant, larger fish reported in 1907 Records of the ova taken at the vari- could have been 3.5 years old, also from ous hatcheries on the Sacramento River The Source of the New Zealand that 1904 release, quite probably with indicate that the ova sent to New Chinook Salmon Runs some smaller, 2.5 year old fish from the Zealand in the period 1901-07 were fall Several questions surround the origin 1905 releases. run fish. New Zealand runs, today, are of the fish that did return to New Zealand With the knowledge of some natural also chiefly in the fall: Some fish begin rivers from about 1906 onwards: spawning by additional fish returning to return to rivers from November (mid— in 1906, observed natural spawning spring) onwards, continuing through 1) Which release did they originate from the 1907 returns to the Waitaki, December and early January (summer). from? plus additional importations and re- However, these early immigrants form 2) What river did the original stock leases of California stocks in 1906 and a continuum with the main run, which come from? 1907, it is obvious that there is no way builds up from late January and through 3) How do the New Zealand runs com- of distinguishing the sources of any re- February and March (fall), with spawn- pare with the source stocks with re- turns after 1907, whether from natural ing occurring from April until June gard to their seasonal occurrence and reproduction, or from one or other of (McDowall, 1990; Quinn and Unwin, age structure? the releases derived from imported ova. 1993). No studies have yet been under- 56(1), 1994 ars nao Figure 3. — Lake Ayson (right), as an elderly man, shown with two assistants, holding adult chinook salmon taken at a trap in the upper reaches of the Waitaki River. taken to determine whether the early, Zealand stocks of chinook grow more land from 1928 onward confirmed this November—December (spring) fish in rapidly than the American counterparts, view (Finlay, N.d.), and this difference any way comprise a stock distinct from up to an age of 3-4 years, but mature remains. the main run of fish in February—March. earlier; earlier maturation may be a re- Conclusion On the face of it, New Zealand seems sult of this more rapid early growth. to have a “fall run” of chinook salmon, In this regard the New Zealand stocks New Zealand’s stocks of anadromous like those from which it was derived. differ from those in California, in which chinook salmon are probably derived The age structure of the runs in most 4-year-olds predominate, with some fish from the second of five consignments New Zealand rivers is as follows: Three- 6 years or even older (Gilbert, 1914; of ova in the early 1900’s. These came year-olds predominate in any brood Flain, 1982). The younger age structure from an undetermined tributary and year; 4-year-olds may be second in in New Zealand dates back at least as hatchery on the Sacramento River, were abundance, but sometimes 2-year-olds early as the 1920’s, as scale samples taken to New Zealand in 1903, reach- are more common; there are very few sent to Charles Gilbert, the noted early ing there early in 1904; the first con- 5-year-olds, and no 6-year-olds or older 1900’s American fisheries biologist, signment (1900 brood year, reaching (Flain, 1982). Pack and Jellyman (1988) were aged and showed that the New New Zealand in early 1901), which is recorded salmon up to 6 years old in Zealand fish were already returning at known to have come from Battle Creek, the Clutha River, but these fish had a younger age than those from which a Sacramento tributary, may have failed reared for several years in inland lakes they were derived in California (N.Z. to produce returns, though there could before emigrating to sea. Quinn and Marine Department, 1927). Further have been a a small and unnoticed re- Unwin (1993) concluded that the New scale samples examined in New Zea- turn from this consignment. The explicit Marine Fisheries Review source in the Sacramento River of the later salmon run. U.S. Dep. Inter., Fish Wildl. Serv., egon, Idaho and Washington. Fisheries shipments cannot now be determined. Res. Rep. 47, 22 p. (Bethesda) 16(2):4-21. Davidson, F. A., and S. J. Hutchings. 1938. The N.Z. Marine Department. 1885-1927. Annual re- geographical distribution and environmental port on fisheries, Wellington. Var. years, var. Acknowledgments limitations of the Pacific salmon (genus pagin. Oncorhynchus). Fish. Bull. (U.S.) 48(26): Pack,Y . M., and D. J. Jellyman. 1988. Fish stocks 667-692. I am grateful to Charles J. Hardy, and fisheries in the lower Clutha River. N.Z. Finlay, H. J. N.d. [ca. 1972]. Report on the ex- Freshwater Fish. Rep. 98, 117 p. Frank W. Fisher, and David G. Hankin amination of the scales of quinnat salmon Quinn, T. P., and M. J. Unwin. 1993. Life his- for assistance in clarifying issues in this t(hOen cdeotrehrymnicnhautsio nt sohfa awgyet sacnhda gr(oWwatlhb aruamte).) N.fZo.r tory patterns of New Zealand chinook salmon paper; to Thomas P. Quinn for advising Mar. Dep. Fish. Tech. Rep. 66, 27 p. (Oncorhynchus tshawytscha) populations. me of the letter from Charles Gilbert; Flain, M. 1982. Quinnat salmon runs 1965-1978 Can. J. Fish. Aquat. Sci. 50:1414-1421. and to Martin J. Unwin for comments in the Glenariffe Stream, Rakaia River, New Rutter, C. 1902. Natural history of the quinnat Zealand. N.Z. Minist. Agric. Fish., Fish. Res. salmon. A report of investigations in the Sac- on the manuscript. Div. Occas. Publ. 28, 22 p. ramento River, 1896-1901. Bull. U.S. Fish. Comm. 22:67-141. Gilbert, C. H. 1914. Age at maturity of the Pa- cific coast salmon of the genus Oncorhynchus. Scott, D. 1984. Origin of the New Zealand sock- Literature Cited Fish. Bull. (U.S.) 32:1-22. eye salmon, Oncorhynchus nerka (Walbaum). Hardy, C. J. 1983. Origin of NZ’s sockeye. Fresh- J. R. Soc. N.Z. 14(3):245-247. Allendorf, F. W., and R. F. Leary. 1988. Conser- water Catch (N.Z.) 18:11-13. , S. J. Hewitson, and J. S. Fraser. 1978. vation and distribution of genetic variation in Hilborn, R. 1992. Hatcheries and the future of The origin of rainbow trout, Salmo gairdneri a polytypic species, the cutthroat trout. salmon in the northwest. Fisheries (Bethesda) Richardson, in New Zealand. Calif. Fish Conserv. Biol. 2:170—184. 17(1):5-8. Game 64:200-209. Ayson, C. L. 1959. Report by Chas. Ayson, 9/10/ 58. Annu. Rep. Waitaki Valley Acclimatisation Lear, W. H. 1980. The pink salmon transplant Thomson, G. M. 1922. The naturalisation of ani- Soc. 1959:23-26. experiment in Newfoundland. Jn J. E. Thorpe mals and plants in New Zealand. Camb. Univ. Ayson, L. F. 1910. Introduction of American (Editor), Salmon ranching, p. 214-243. Acad. Press, U.K., 607 p. fishes into New Zealand. Fish. Bull. (U.S.) Press, Lond. U.S. Bureau of Fisheries. 1904-1907. Report of 28:969-975. Leitritz, E. 1970. History of California’s fish the U.S. Fisheries Commission. Var. years, var. Bakshtansky, E. L. 1980. The introduction of pink hatcheries 1870-1950. Calif. Dep. Fish Game, pagin. salmon into the Kola Peninsula. Jn J. E. Fish Bull. 150, 92 p. U.S. Commission of Fish and Fisheries. 1902 and Thorpe (Editor), Salmon ranching, p. 245- McDonald, J. 1981. The stock concept and its 1903. Report of the Commissioner. Var. nos., 260. Acad. Press, Lond. application to British Columbia salmon fish- pagin. Behnke, R. J. 1992. Trouts of western North eries. Can. J. Fish. Aquat. Sci. 38:1657—1664. America. Am. Fish. Soc. Monogr. 6, 275 p. McDowall, R. M. 1988. Diadromy in fishes: White, R. J. 1992. Why wild fish matter: Bal- Berg, M. 1977. Pink salmon, Oncorhynchus Migrations between freshwater and marine ancing ecological and aquacultural fishery gorbuscha (Walbaum) in Norway. Rep. Inst. environments. Croom Helm, Lond., 308 p. management. Trout 33(4):17—33, 44-48. Freshwater Res., Drottningholm 56:12-17. . 1990. New Zealand freshwater fishes: Zamorano, R. M. 1991. Salmon farming in Chile. Childerhose, R. J., and M. Trim. 1979. Pacific a natural history and guide. Heinemann-Reed, In R. H. Cook and W. Pennell, (Editors), Pro- salmon and steelhead trout. Douglas and Auckland, 553 p. ceedings of the special session on salmonid MacIntyre, Vancouver, B.C., 158 p. Nehlsen, W., J. E. Williams, and J. A. aquaculture, World Aquaculture Society, Feb- Cope, E. B., and D. W. Slater. 1957. Role of Lichatowich. 1991. Pacific salmon at the ruary 16, 1989, Los Angeles, U.S.A. Can. Coleman hatchery in maintaining a king crossroads: stock at risk from California, Or- Tech. Rep. Fish. Aquat. Sci. 1831:51-63. 56(1), 1994 Survey Assessment of Semi-—pelagic Gadoids: The Example of Walleye Pollock, Theragra chalcogramma, in the Eastern Bering Sea WILLIAM A. KARP and GARY E. WALTERS Introduction To address this problem, survey ob- is generally found in pelagic and dem- jectives should be evaluated. If the as- ersal regions over bottom depths of 25— Direct assessment provides essential sessment process requires a survey- 400 m, although it does occur in the information for the management of based estimate of overall abundance, pelagic zones of deeper waters (Sample many marine fish stocks. Frequently, problems associated with combining the and Bakkala, 1989). Greatest abun- demersal stocks are assessed by means two sets of data require careful consid- dances are found along the outer conti- of bottom trawl surveys, and pelagic eration. But if it is satisfactory to pro- nental shelf over water depths of 100- stocks are assessed using acoustic tech- vide indices of the abundance of cer- 300 m (Wespestad and Megrey, 1990). niques together with some form of di- tain portions of the stock, such as spe- Scientists from the NMFS Alaska Fish- rect sampling such as midwater trawl- cific age groups, it may be possible to eries Science Center (AFSC) conduct ing. Each approach has its own strengths consider the pelagic and demersal as- the assessment of this stock. The dem- and limitations but these types of rou- sessments as independent sources of ersal component of the stock is assessed tine surveys provide critical information information, and problems associated annually during a multi-species bottom for many stocks. with combining data sets would then be trawl survey of the EBS shelf. Small- When a stock is semi-pelagic (or of less concern. scale surveys began in the early 1970's, semi-demersal) in habit, however, it is The walleye pollock, Theragra chal- and the present survey coverage was difficult to accomplish overall assessment cogramma, resource of the continental first established in 1975 and has been with a single technique, and it may be shelf and slope of the Eastern Bering done annually since 1979. Also begin- necessary to assess the pelagic and dem- Sea (EBS) supports major fisheries ac- ning in 1979, an expanded triennial bot- ersal components independently. Because tivities. The species is semipelagic and tom trawl survey has been conducted; the biases associated with each technique this has covered a greater area of the differ, difficulties may be encountered The authors are with the Alaska Fisheries Sci- shelf and the waters of the upper conti- when attempting to combine the data to ence Center, National Marine Fisheries Service, nental slope. During the triennial sur- NOAA, 7600 Sand Point Way N.E., Seattle, WA produce a comprehensive estimate. 98115. veys, the pelagic component of the pol- ABSTRACT — Assessment of walleye pol- ing the lower 3 m of the water column. To- creased, so has the relative proportion of lock, Theragra chalcogramma, in the east- tal population estimates have ranged from pollock estimated by the demersal surveys. ern Bering Sea is complicated because the 134 x 10° fish in 1979 to 27 x 10° fish in Consequently, it is unlikely that either tech- species is semi-pelagic in habit. Annual 1988. The very high abundance observed nique can be used independently to moni- bottom trawl surveys provide estimates of in 1979 reflects the appearance of the un- tor changes in abundance and age compo- demersal abundance on the eastern Bering usually large i978 year class. Changes in sition. Midwater assessment depends on Sea shelf. Every third year (starting in age-specific abundance estimates have pelagic trawl samples for size and age com- 1979), an extended area of the shelf and documented the passage of strong (1978, position estimates, so both surveys are sub- slope is surveyed and an echo integration— 1982, and 1984) and weak year classes ject to biases resulting from gear perfor- midwater trawl survey provides estimates through the fishery. In general, older fish mance and interactions between fish and of pollock abundance in midwater. Overall are more demersally oriented and younger gear. In this review, we discuss survey age-specific population and biomass esti- fish are more abundant in midwater, but this methodology and evaluate assumptions re- mates are obtained by summing the demer- trend was not always evident in the patterns garding catchability and availability as they sal and midwater results, assuming that the of abundance of 1— and 2—year-old fish. As relate to demersal, midwater, and overall bottom trawl samples only pollock inhabit- the average age of the population has in- assessment. Marine Fisheries Review