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Alaska Fishery Research Bulletin Issues, Vol.5 No. 1 - Summer 1998
The Diets and Feeding Habits of Some Deep-Water Benthic Skates (Rajidae) in the Pacific Waters Off the Northern Kuril Islands and Southeastern Kamchatka
Alexei M. Orlov - Vol. 5(1):1-17. 1998.
On the basis of shipboard analysis, the diets of 7 species of deep-benthic skates were examined: Aleutian skate Bathyraja aleutica, sandpaper skate B. interrupta, Alaska skate B. parmifera, B. matsubarai, whiteblotched skate B. maculata, whitebrow skate B. minispinosa, and Okhotsk skate B. violacea. The diet of predatory skates (Alaska skate, Aleutian skate, whiteblotched skate, and B. matsubarai) consisted of large crustaceans, cephalopods and fishes. Benthophagic skates (sandpaper skate, Okhotsk skate, and probably whitebrow skate) consumed mainly amphipods and worms. The consumption of worms and crustaceans (especially small crustaceans) in diets of predatory skates declined with increasing skate size, whereas cephalopod and fish frequency of occurrence increased. For benthophage skates occurrence of amphipods in stomachs declined with increasing skate size and consumption of shrimps and other large crustaceans, as well as squids, increased.
Full Article (PDF 577 kB)Relationship Between Wind and Year Class Strength of Tanner crabs in the Southeastern Bering Sea
Gregg E. Rosenkranz, Albert V. Tyler, Gordon H. Kruse, and H. Joe Niebauer - Vol. 5(1):18-24. 1998.
Knowledge of Bering Sea oceanography and the life history of Tanner crabs Chionoecetes bairdi led us to 2 hypotheses about the effects of wind on the formation of year class strength, defined as the number of crabs hatched in a given year that survive to maturity. First, year class strength is limited by food availability during the pelagic zoeal phase and is enhanced when wind-driven turbulent mixing or upwelling transports nutrients into the euphotic zone, increasing primary and secondary productivity. Second, wind-driven advection during the pelagic phase carries zoeae to either favorable or unfavorable habitat for settlement. We investigated these hypotheses by testing for statistically significant correlations between recruitment estimates, derived from a length-based model, and wind data from St. Paul Island in the eastern Bering Sea. We found a significant positive correlation between the intensity of average May-June wind vectors resolved along NE-SW axes and recruitment of male Tanner crabs 7 years later and female Tanner crabs 6 years later; there were no significant relationships when winds were resolved along NW-SE axes. Despite uncertainty about age of recruitment due to our poor understanding of Tanner crab growth rates, we interpret these statistical results as lending support for both the above hypotheses.
Full Article (PDF 61 kB)An Economic Analysis of Pot Limits for the Adak Brown King Crab Fishery: A Distinction Between Open Access and Common Property
Mark Herrmann, Joshua Greenberg, and Keith Criddle - Vol. 5(1):25-38. 1998.
A proposed vessel-specific pot limit for the Adak, Alaska, brown king crab Lithodes aequispina fishery failed to be adopted as regulation by the Alaska Board of Fisheries at their March 1997 meeting. A group of fishermen had proposed the pot limit because they believed excessive pot gear on the crabbing grounds had compromised effective management. We suggest that a manageable system of quasi property rights exists in the fishery and that the proposed pot limits would have failed to improve, and could have decreased, economic efficiency. Second, in the absence of a reliable efficiency rationale, the proposed vessel-specific pot limits were solely allocative in purpose. Furthermore, management's goal in this fishery is focused on controlling total fleet fishing power rather than the number of pots fished by individual vessels. If these assertions are true, then it may be preferable to consider the development of alternative regulatory measures that effectively address total rather than per-vessel fishing power.
Full Article (PDF 162 kB)Avoidance Behavior of Ovigerous Tanner Crabs Chionoecetes bairdi Exposed to Mine Tailings: A Laboratory Study
Scott W. Johnson, Robert P. Stone, and D. C. Love - Vol. 5(1):39-45. 1998.
Avoidance behavior was examined in ovigerous Tanner crabs Chionoecetes bairdi exposed to mine tailings produced in a pilot plant associated with a proposed gold mine near Juneau, Alaska. Individual crabs were placed in a circular tank that was divided into 4 equal sections containing natural marine sediment (control) and tailings in alternate sections. A time-lapse video camera recorded the position of each crab within the tank over 24 h. Crabs spent significantly (t = 2.43, P < 0.02, df = 24) more time on control sediment (61%) than on tailings (39%). Of 25 test crabs, 19 spent the most time (greater than or equal to 12 h) on control sediment, whereas only 6 crabs spent the most time on tailings. Ovigerous Tanner crabs may avoid areas affected by the submarine disposal of tailings during the life of the mine. Location of potential submarine tailings disposal sites in areas with high natural sedimentation may accelerate recovery of the sea floor by rapid burial of tailings.
Full Article (PDF 49 kB)Genetic Variation of Return Date in a Population of Pink Salmon: A Consequence of Fluctuating Environment and Dispersive Selection?
William W. Smoker, Anthony J. Gharrett, and Michael S. Stekoll - Vol. 5(1):46-54. 1998.
A genetic basis for variation in the date that anadromous salmon return to their natal or home stream was demonstrated by significant differences between return dates of pink salmon Oncorhynchus gorbuscha families. Of 120 families made by hierarchical matings of 60 males and 120 females, 118 families survived. The first half (60 families) and second half (60 families) were spawned 28 d apart. The 120 full-sibling families were incubated separately, released as fry with identifying coded microwire tags, and recovered entering the home stream as adults. Families in the first half returned on average 29 d before families in the second half (P < 0.0001). Average return dates differed between families that were spawned on the same day by different fathers (P < 0.045 sons; P < 0.040 daughters). These differences indicate that additive genetic variance contributes to the natural variation of return date. Heritability of timing of anadromous migration in odd-year pink salmon spawned in Auke Creek, Alaska, was very high, perhaps near unity, over the entire population. For segments of the population spawning on the same date, heritability was about 0.2 (SE 0.2) in males and about 0.4 in females (SE 0.2). We suggest that such high genetic variability of a trait closely related to fitness is maintained by the fluctuating environment to which Auke Creek pink salmon must continually adapt or by dispersive selection caused by redd superimposition. In either case, generalizing to other salmon populations, rational management must preserve variability of return timing if the fitness of populations is to be conserved.
Full Article (PDF 67 kB)Salmon Run Failures in 1997-1998: A Link to Anomalous Ocean Conditions?
Gordon H. Kruse - Vol. 5(1):55-63. 1998.
In July 1998 Alaska's Governor Tony Knowles submitted a request for federal disaster relief owing to severe economic and social hardships in some western Alaska communities affected by unusually poor salmon runs, especially Bristol Bay sockeye salmon Oncorhynchus nerka and Yukon River chinook O. tshawytscha and summer chum O. keta salmon. Other anomalies were also noted in these runs: late run timing, smaller-than-average fish, altered migration pathways, and anecdotal reports of higher occurrences of parasites and increased signs of predation. Were these poor returns attributable to unusual marine environmental conditions in 1997/98? Decadal changes in salmon productivity have been related to indices of the strength of the Aleutian Low in winter, which may affect feeding success during early marine life. Analysis of return-per-spawner data is needed to determine whether this climate-salmon relationship continues to hold. Additionally, significant changes in ocean conditions occurred in the North Pacific and Bering Sea in 1997/98 that may have had profound effects on the marine ecosystem. Not only was there a very strong equatorial El Niño, but light winds, low nutrients, and high solar radiation led to the first-recorded bloom of coccolithophores in the Bering Sea in summer 1997 and a bloom occurred again in spring 1998. At-sea research is urgently needed on the biotic implications of these conditions, from effects on primary and secondary producers to effects on invertebrates, fish, birds, and marine mammals through the pelagic and benthic food webs.
Full Article (PDF 71 kB)Occurrence of an Atlantic Salmon Salmo salar in the Bering Sea
Richard D. Brodeur and Morgan S. Busby - Vol. 5(1):64-66. 1998.
An immature male specimen of an Atlantic salmon Salmo salar was captured in a bottom trawl south of the Pribilof Islands in the Bering Sea in September 1997; this represents the first known capture of this species in the Bering Sea. We provide information on the size, age, and feeding of this fish and discuss the ecological implications of this occurrence.
Full Article (PDF 71 kB)A Comment and Response on Time Series Outlier Analysis
Comment: Steven R. Hare and Robert C. Francis and Response: Edward V. Farley, Jr. and James M. Murphy - Vol. 5(1):67-73. 1998. No Abstract.
Full Article (PDF 78 kB)