Now showing items 1-16 of 16

• #### A Maritime Sense Of Place: Southeast Alaska Fishermen And Mainstream Nature Ideologies

This thesis portrays Southeast Alaska fishermen's 'senses of place' on the sea, elicited through interviews. The distinctiveness of a fishing culture, and the demands and opportunities of the occupation and environment, result in a relationship to place different from the majority society. Themes discussed include being at home on the sea, the environment as a basis for occupational choice, territorial flexibility, preference for wild nature, and wild nature produces exploitatable surpluses. The variability of the environment affects patterns of learning, models of nature, and values in inter-personal interactions. Relationship to 'place' is found to be central to the culture, but as the area becomes identified by outsiders as "wilderness," national environmental organizations and others regard fishermen as 'out of place'. Differences from modern Western society in relationship to 'place' and 'nature', highlighted by the Glacier Bay National Park case, are proposed to explain negative perceptions of these fisheries. <p>
• #### Carbon And Nitrogen Flows In Zero -Water Exchange Shrimp Culture: Inferences Using Stable Isotope Tracers

Nutrient and energy flow in cultures of Pacific White Shrimp, Litopenaeus vannamei, were examined in zero-water exchange, 1200--1300 L mesocosms at the Oceanic Institute (OI), Waimanalo, Hawaii. A technique was developed for monitoring shrimp use of formulated feeds through the addition of stable isotopically labeled nutrients to the feed ingredients. Crystalline amino acid compounds were ineffective as labels due to their rapid dissolution in the tank water with feed pellet break-up. Labels which were 'packaged' as algal cells prior to addition to the feed pellets were more effectively incorporated into shrimp tissues than crystalline label (approximately 27% versus 8% for crystalline label). The 'packaged' label technique was also used to test soluble proteins from pollock processing wastes (stickwater) as a feeding stimulant for Litopenaeus vannamei. Indoor controlled condition experiments and outdoor experiments with natural pond biota compared stickwater amended feed to squid liver powder amended feed for growth and assimilation by the shrimp. Initial results indicated that pollock processing by-products might function as a feeding stimulant in shrimp aquaculture. The addition of 15N-ammonium to outdoor shrimp tanks showed that natural tank production contributed significantly to shrimp growth requirements providing between 17 and 77% of the growth nitrogen. When labeled ammonium was added to black covered tanks, shrimp had slower growth rates (0.5 g/wk as compared to 0.7 g/wk for uncovered ammonium addition tanks) but significant uptake of this label, with a tank biota contributing 23%. This finding supported a bacterial role in shrimp nutrition that will require further study. Isotopic analysis of individual amino acids in shrimp muscle from outdoor tanks with and without added 15N-ammonium further established the role of tank natural populations to shrimp nutrition. Rapid increases in delta 15N for threonine one day after label addition suggested an increased requirement for this essential amino acid. Further identification of the contribution of tank biota to shrimp amino acid profiles will require profiles of the delta 15N of specific amino acids for suspended particulate organic matter.
• #### Ecological effects of spawning salmon on several southcentral Alaskan streams

The ecological effects of salmon (Oncorhynchus spp.) carcasses on southcentral Alaskan streams were studied by: (1) observing salmon carcass decomposition and use; (2) comparing the macroinvertebrate community structure of streams receiving different inputs of salmon carcasses; and (3) quantifying the amount of marine-derived nitrogen (MDN) entering stream food webs using stable-isotope analysis. Abiotic mechanisms, such as large woody debris and the slow waters of stream margins and eddies were important in initial retention of salmon carcasses. Once entrained, carcasses decayed rapidly due to intense microbial processing. Stream insects and fishes were observed consuming carcasses, eggs, and smolts. Macroinvertebrate communities in streams receiving runs of salmon or in lake outlet streams were more diverse taxonomically. One functional feeding group, filterers (including net-spinning caddisflies (Hydropsychidae) uncommon in Alaska), increased in relative abundance. Although many other taxa also responded positively to enrichment, some taxa responded negatively. A significant difference existed in $\partial\sp{15}$N values between MDN and terrestrial sources but natural dissolved inorganic nitrogen contributions to stream food webs ($\approx$90-95% of total N) from groundwater generally overwhelmed the marine signal ($\approx$5-10% of total N). $\partial\sp{15}$N values generally suggested that some MDN ($\approx$15% of total N) entered into food webs after its incorporation into algal biomass but values for certain macroinvertebrate taxa (Arctopsyche and Plumiperla), salmon fry (Oncorhynchus spp.) grayling (Thymallus arcticus), rainbow trout (O. mykiss) and American dippers (Cinclus mexicanus) suggest these biota directly consume substantial amounts (40%-90%) of salmon protein. $\partial\sp{15}$N values in individual macroinvertebrate taxa usually cycled seasonally. All three elements of this investigation support the hypothesis that salmon carcasses can be important in structuring aquatic food webs.
• #### Effects of density-dependence, environment and species interaction during spawning and incubation on population dynamics of pink and sockeye salmon in the Auke Lake system, southeast Alaska

Mechanisms that regulate or influence fry and smolt production of pink and sockeye salmon in the Auke Lake system, southeast Alaska, were studied with special emphases on effects of: (1) density-dependence; (2) environmental effects; and (3) species interaction. There has been an increasing trend in the residuals of spawner-recruit models for pink and sockeye salmon since the late 1970's. A strong positive influence of precipitation was found in sockeye smolt production. Estimated spawner capacity of pink salmon was 15 times greater than sockeye salmon in the system. Pink salmon spawners varied in stream life (5-11 days), spawning efficiency (30-70% of daily cohorts of females retained less than 500 eggs at death), and habitat selection (30-70% spawned in Auke Creek rather than Lake Creek, the inlet stream). Variation of these attributes in female pink salmon was explained by various environmental variables using generalized linear models. Repeated use of limited spawning grounds by Pacific salmon, i.e., redd superimposition, can cause density-dependent mortality. Pink salmon egg loss from part of Auke Creek, estimated by a series of mark and recapture experiments, was roughly proportional to spawner abundance and not related to discharge. The maximum daily egg loss was estimated to be 3-400,000 eggs. Eggs in samples were more advanced in development later in the season. Eggs were washed out from the streambed due to redd superimposition; eggs spawned by early pink salmon spawners suffered higher mortality than eggs spawned by later spawners. The peak sockeye spawning preceded the peak pink spawning by approximately one week in Lake Creek, and the major spawning areas of sockeye salmon occurred approximately 250-350 m upstream from those of pink salmon. Microhabitat selection measured by four variables differed significantly between the species, but discrimination between the species was impossible because of large overlaps. Habitat variation was greater among different runs of sockeye salmon than between the two species. Sockeye salmon shifted spawning sites from riffles to pools as the season progressed.
• #### Forecasting catches of Pacific salmon in commercial fisheries of southeast Alaska

Data collections since 1911 and statistical methods from time series analysis are employed to forecast catches of pink, chum, coho, and sockeye salmon in Southeast Alaska. Knowledge of the spatial and temporal domains favored by Pacific salmon originating in Southeast Alaska is summarized to provide a basis for estimating environmental variation experienced by each species. Catches in northern, southern, and all of Southeast Alaska are forecast with univariate ARIMA, transfer function-noise (TFN), and vector ARMA models. Univariate models for catch in numbers and catch in weight yielded similar results for each species. Air and sea surface temperatures, freshwater discharge, and coastal upwelling enter TFN models for several species and areas. Environmental variables allow TFN models to explain a small amount of variation in the catches (average of 19%) above that explained by univariate models. Forecasts for most, but not all, species and areas are improved (average of 16%) by including environmental data in TFN models. Stock-recruit models with a parameter for density dependent mortality provide the best forecasts of pink salmon catch and are recommended for future forecasts. Winter air and sea surface temperatures enter stock-recruit models for pink salmon, and forecasts of catch and recruitment in northern and southern Southeast Alaska tend to oppose each other and cancel (1981-1985), which suggests that the salmon are caught in areas other than where they originated. Mean absolute percentage error (MAPE) for forecasts of pink salmon catch from stock-recruit models in Southeast Alaska, based on data for 1981-1990, is estimated at 49%, with first, second, and third quartiles of 10%, 23%, and 83%, respectively. Catches of Pacific salmon in Southeast Alaska are significantly correlated and are forecast jointly with good accuracy by vector ARMA models, except when effects believed to result from density dependent mortality are present in the data. Correlations indicate that coho salmon smolts might prey on young pink salmon. Also, recruitment of pink salmon in Southeast Alaska and British Columbia is correlated; regional environmental influences might thus affect catches in both areas. In Southeast Alaska, MAPE for forecasting coho and sockeye salmon catch with time series analysis is about 20%, and about 30% for chum salmon.
• #### Influences of abiotic factors on the return, ocean abundance, and maturity of sockeye salmon (Oncorhynchus nerka) in the northern North Pacific Ocean

The fluctuations in return, ocean abundance, and maturity of sockeye salmon (O. nerka) were examined and related to wind stress curl, sea suface temperature (SST), sea level pressure, and cloudiness, in the area between 40$\sp\circ$N-60$\sp\circ$N and 160$\sp\circ$E-140$\sp\circ$W. Historical records, during two periods, 1971-76 and 1955-86, were the primary source of data. Spectral analysis of a 360-month period of mean wind stress curl during 1955-85 showed 3.1- and 5.3-year cycles. The 5.3-year cycle was correlated (r =.32 to.44, P $<$.10) with the return of Bristol Bay sockeye salmon mostly at 0- (the year of spawning migration) and 1-year lag (the first year of lake residence). The relative ocean abundance of sockeye salmon in the northwestern Northern Pacific during 1971-76 was lowest during the three periods: 1961-70, 1971-76, and 1977-85. Mature Kamchatka sockeye salmon were 24% more abundant than mature Bristol Bay sockeye salmon during 1971-76. A significant relationship was found between the May-June mean SST and abundance of sockeye salmon (r =.56 to.66, P $<$.01) during 1961-85. In the northern North Pacific, the SST was positively (r =.73 to.86, P $<$.001) related with the gonad weight of sockeye salmon. The results indicated a close relation between the return, ocean abundance, and maturity of sockeye salmon and most of the abiotic factors.
• #### Seasonal sea ice, the cold pool and gadid distribution on the Bering Sea shelf

The variability in winter seasonal sea ice cover, its impact on the summer hydrography of the Bering Sea shelf, and the consequences to the demersal distributional patterns of walleye pollock (Theragra chalcogramma) and Arctic cod (Boreogadus saida) were investigated. Winter ice conditions acquired by remote sensing techniques were compared to the following summer's hydrographic conditions and fish distributions acquired from fisheries surveys between 1972-1993. Linkages among atmospheric, oceanic, and biological interactions occurred on two scales, an interannual mode of warm or cold conditions and multi-annual regimes of warm, cold or mixed conditions. The southernmost extent of sea ice as measured along meridian 169$\sp\circ$W (P$\sb{\rm S}$) can be used to identify warm or cold conditions on the shelf. Warm conditions occurred when P$\sb{\rm S}$ extended southward, between 60$\sp\circ$-$57\sp\circ30\sp\prime$N, bottom temperatures were 3.8$\sp\circ$-4.6$\sp\circ$C and the subsurface cold pool of water extended eastward, between meridians 170$\sp\circ$-166$\sp\circ$W. Cold conditions occurred when P$\sb{\rm S}$ extended southward, between $57\sp\circ30\sp\prime$-56$\sp\circ$N, bottom temperatures were 1.2$\sp\circ$-3.0$\sp\circ$C and the subsurface cold pool of water extended eastward, between meridians 163$\sp\circ$-158$\sp\circ$W. During the 20 year time series of climatic conditions, three regimes occurred: a cold regime prevailed from 1972-1977, a warm regime from 1978-1984, and a mixed regime from 1985-1991. Age-1 and age-2 and older walleye pollock were primarily in the outer domain during cold conditions and in the middle and inner domain during warmer conditions. Arctic cod were present during cold conditions. Shifts in distribution of these species have ecosystem-wide consequences and can occur on either interannual scales or on the time-scale of regime shifts. Changes in the level of piscivorous predation on age-1 pollock, including cannibalism, occurred on the annual scale while prey species of seabirds and marine mammals fluctuated on the regime scale. Warm or cold summertime conditions were predictable from the previous winter's ice extent, which provides basic information on the level of environmental variability that affects biological systems and can be utilized in modeling this system. The results predict that older pollock will be concentrated in the outer domain following winters with extensive ice, information which could be useful to the fishing industry.

• #### Structure and growth of Pacific halibut otoliths: Identifying spatial and temporal variation

Otoliths are polycrystals of calcium carbonate and protein that grow through the process of biomineralization within the otic capsule of teleost fish. Otoliths of Pacific halibut (Hippoglossus stenolepis) are routinely collected to provide age information, but other information has not been examined in detail. The purpose of this study was to investigate whether otolith structural patterns reveal information about otolith growth, and by inference, about fish growth and habitat during its early life. Variation in the increment widths of the first five annuli of adult halibut otoliths over a 26 year period were partitioned in two ways: the year the growth took place and the year-class to which the fish belonged. The year of growth explained temporal variation in the youngest ages and was attributed to changes in temperature which may influence recruitment success, while the year-class of growth explained temporal variation in older juveniles, but could reflect sampling bias. An analysis of microstructure increments indicated that relative otolith growth rate was an indicator of larval somatic growth. Young halibut from the Gulf of Alaska exhibited similar larval growth histories, though individual and nursery area differences were apparent. Specimens from the Bering Sea had slower larval growth rates than halibut from the Gulf of Alaska. Trace levels of strontium within otoliths were associated with ontogenetic changes of larvae and winter annuli formation of adults. Levels of potassium and sodium varied by nursery area of capture suggesting some utility for stock separation, though there was indication of significant interannual variation. The shape of the larval crystal within the otolith microstructure of young halibut was found not to be associated with nursery area of capture, and thus is not a good candidate as a stock separation tool. The high variation within individuals suggests that the shape of the crystal is not determined by external events. Overall, several patterns preserved in otoliths can provide insight into processes that influence the growth of halibut and distribution of individuals and these patterns can be recovered from adult fish. However careful interpretation is still required to separate meaningful information from spurious data.
• #### The Economic Value Of Alaska'S Copper River Personal-Use And Subsistence Fisheries: An Application Of The Zonal Travel Cost Model

The salmon harvest on the Copper River, Alaska, is shared by commercial, sport, personal-use and subsistence fishers. An important and reoccurring issue is the allocation of salmon harvest among these user groups. Economic analyses, along with biological, legal, social and cultural considerations, have the potential to help policy makers appreciate the consequences of alternative allocations. Although economic analyses of the commercial and sport fisheries have been completed, no comparable studies exist for the personal-use and subsistence fisheries. The zonal travel cost method (TCM) is used to estimate the net economic value (consumer surplus) of the Copper River Basin personal-use and subsistence fisheries. The nature of the fishery and the data set is especially well suited for this purpose. <p>
• #### The red king crab fishery: handling effects, bait efficiency, and pot behavior

Red king crabs (Paralithodes camtschaticus) are caught by pots in a male-only fishery in Alaska. The objectives of this research were: (1) to examine impacts of the commercial fishery on discarded female and sublegal male crabs; (2) to examine bait efficiency; (3) to document crab behavior to pots; and (4) to develop a model describing catch versus soak time. I estimated from observer data that 64.6% of crabs in the Bering Sea fishery were females and sublegal males; I simulated commercial crab handling procedures in the laboratory to test effects on discarded crabs. Although body damage increased significantly with increased handling, there were no significant effects on righting time, feeding rate, weight gain, carapace length increment, or survival. I examined the efficiency of five potential baits (squid, herring, mussel, king crab muscle, and king crab ovary) by observing chemoreception and feeding behavior of the crabs. Chemosensory threshold varied between $10\sp{-4}$ to $10\sp{-6}$ g.L$\sp{-1}$, and feeding threshold ranged from $10\sp{-2}$ to $10\sp{-3}$ g.L$\sp{-1}.$ Crabs were most sensitive to the extract of conspecific muscle, while herring was most effective in arousing feeding behavior. Little difference existed between males and females in chemoreception and feeding behavior. Behavioral responses of the crabs to crab pots were observed by time-lapse video. Crabs approached the pot from downstream, and 78.3% of crabs searched less than 90$\sp\circ$ before leaving or entering the pot. The entry success rate was 8.1%. Only large males could begin escape from the bottom panel. Crabs had difficulties in accessing the pot and in escaping from inside the pot. The standard pot appeared inefficient in catching legal males, while it retained many non-legal crabs. I constructed a general model to describe the relationship between catch and soak time for trap fisheries. The model is expressed as $C\sb{t}=ab+a(t-b)\ e\sp{-ct},$ where $C\sb{t}$ is the catch per trap haul at soak time t, and a, b, and c are parameters to be estimated. This model is suitable for both short and long soak times.
• #### The significance of marine-derived biogenic nitrogen in anadromous Pacific salmon freshwater food webs

The natural abundance of the stable isotope ratios $\sp{15}$N/$\sp{14}$N and $\sp{13}$C/$\sp{12}$C expressed as $\delta\sp{15}$N and $\delta\sp{13}$C was used to trace biogenic nutrients delivered by returning adult anadromous Pacific salmon into freshwater systems. These systems were Sashin Creek, a rapidly flushing stream located on Baranof Island, southeastern Alaska and Iliamna Lake, the major sockeye salmon, Oncorhynchus nerka, nursery lake in the Kvichak River watershed, Bristol Bay, southwestern Alaska. Marine-derived nitrogen (MDN) was quantifiable by use of an isotope mixing model based on comparison of biota $\delta\sp{15}$N in areas used for spawning by anadromous salmon with salmon-free controls within the same watershed. Control periphyton (benthic primary producers) $\delta\sp{15}$N values $\sim$0 suggested that the control N pool was derived from N$\sb2$ fixation without significant recycling. In contrast, periphyton abundant in areas of intense spawning activity or carcass aggregation had $\delta\sp{15}$N $\sim$ +7. These two values were the basis for comparison of $\delta\sp{15}$N values of higher trophic level biota. A mixing model relating $\delta\sp{15}$N to MDN with trophic level was used to estimate consumer MDN through incorporation of a priori isotopic trophic enrichment factors established in the literature. Distinctive $\delta\sp{13}$C signatures along the Sashin Creek stream gradient and between Iliamna Lake littoral and limnetic production were used in concert with $\delta\sp{15}$N. Sashin Creek fishes reflected isotopic signatures of periphyton and thus production within the same stream section. Isotopic data suggested an overall importance of limnetic production in Iliamna Lake resident fish and juvenile sockeye salmon diets. Salmon eggs and emergent fry retaining the parental marine isotopic signature were distinguishable from autochthonous production derived from marine N, and appear to be a minor dietary component in both Sashin Creek or Iliamna Lake fishes. The proportion of MDN in resident fish N, including juvenile salmon after turnover of the natal N pool, was proportional to the escapement of spawners. Thus there is now direct evidence for a significant natural fertilization process: the flow of remineralized marine-derived biogenic nutrients from returning anadromous Pacific salmon into freshwater food webs.
• #### Three-dimensional diving behavior of ringed seals

The three-dimensional movements of 13 freely diving ringed seals were recorded during the spring of 1990, 1991, 1992, 1996, and 1997 in the Canadian Arctic near Resolute Bay, Nunavut. These data were used to investigate the diving behavior of ringed seals more fully than was possible using previous data, which only recorded the vertical movements of diving animals (time-depth data). During a third of all dives, ringed seals focused much of their effort within a reduced volume, suggesting local search behavior within patches of prey. Local search occurred during descent, ascent, and bottom phases (time spent at depth between the end of descent and the beginning of ascent) of dives, but local search most commonly occurred during bottom phases. Location data from five seals were detailed enough to allow analysis of three-dimensional movements within individual dives. Behaviors were defined for the dives of these five seals based on the character of movements within the dives. Ringed seal dives included horizontally convoluted, travel, and exploration dives, but vertically convoluted, rest, and sit-and-wait foraging dives were not observed. Horizontally convoluted (presumed foraging), travel, and exploration dive behaviors were defined with similar frequency for V-shaped dives (dives with only descent and ascent phases) and U-shaped dives (dives with descent, bottom, and ascent phases). The lack of behavioral differences between dives with distinct time-depth profiles suggested that time-depth profiles were not a reliable means of classifying behavioral dive types for ringed seals.