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Networks play a key role in the functioning of socioecological fishery systems. Most network studies among fish harvesters examining fishing success utilize interviews and questionnaires. Though insightful, such studies are resource and time-intensive and thus unlikely to be replicated frequently through time. Alternatively, commercial landings records and vessel monitoring systems (VMS) provide continuous sources of information that can be used to examine variation in vessel networks through time. We used VMS data to define association networks among vessels. Relationships were found between common network metrics and annual performance based on landings data. Associations between vessels were more closely examined as a function of annual activity, performance, favoured species, and landing port using temporal exponential random graph models. We examined network dynamics across 4 consecutive years. Changes in vessel associations were clearly related to performance, landing port, and species targeted. Network structure could affect the relationship between catch and nominal effort, influencing stock assessments and responses to management actions. Our methodology provides a means to follow network change, identifying situations where more detailed study is warranted. [ABSTRACT FROM AUTHOR]

The interaction between an organism and its environment is a major determinant of an individual's growth rate, longevity, and fitness. Such interactions and resultant variation in growth is particularly prevalent in salmonids where a diversity of life history types and morphotypes can be observed within a single ecosystem. Lake trout, Salvelinus namaycush, are typically considered freshwater residents. However, three life history types within the Husky Lakes estuary and connected lakes, NWT were recently documented, including semi-anadromous, brackish-water resident, and freshwater resident. To understand how use of brackish-water environments influences growth and longevity in lake trout, we assessed otolith increment widths, as a proxy for annual fish growth, and age-at- capture among life history types. Assessment of increments indicated that growth increased in brackish water for semi-anadromous lake trout, and that growth was faster for semi-anadromous and brackish-water residents than for freshwater residents (70 mm larger on average at age 15). In addition, age at capture was significantly older in brackish-water residents (3.8 years older) when compared to the other life histories. Together these results indicate that life in brackish water can have positive effects on growth and longevity for lake trout. [ABSTRACT FROM AUTHOR]

The objective identification of targeting behavior in multispecies fisheries is critical to the development and evaluation of management measures. Here, we illustrate how the statistical distribution of commercial catches can provide information on species preference that is consistent with economic data but not a simple function of price. Using the Dutch beam trawl fishery from 1998 to 2003, we show that the distribution of the log10-transformed catch rates of preferred species exhibit greater negative skews than less preferred species. Furthermore, subsets of the fleet employing spatially distinct strategies generate the expected patterns in the skews of their catch distributions. A simple model is presented to illustrate a behavioral mechanism for variation in skews and identify circumstances where it could apply. As a result of this analysis we propose that (i) catch distributions should be examined by species when investigating targeting behavior and (ii) changes in error structure over time can be expected in comparisons of catch statistics such as those used to create abundance indices or estimate fishing power. [ABSTRACT FROM AUTHOR]

Throughout the 1990s, the Gulf of St. Lawrence snow crab (Chionoecetes opilio) harvest provided an example of effective co-management in a developing fishery. The Department of Fisheries and Oceans Canada (DFO) and the snow crab fleet (the fleet) shared information that coordinated management and exploitation throughout the season. A preseason survey by DFO provided resource distributions prior to the fishery's opening. In-season monitoring allowed managers to track spatial and temporal variation in crab availability. This level of detail allowed the application of the ideal free distribution as a management and conservation tool. However, proper justification for its application requires the demonstration of information exchange and competitive effects. The spatial distribution of effort suggests that both of these are present. Fishing effort was influenced by public information and potential information exchange within the fleet. Reduced aggregation at smaller spatial scales suggests competition in trap placement. Thus, increasing fleet size may have a disproportionately small impact on fishing mortality because of limitations in information exchange and the lack of personal information in the new vessels. However, the nonlinear relationship between crab abundance and catch rates suggests that managers should avoid policies that increase fishing effort during times of low crab abundance. [ABSTRACT FROM AUTHOR]

Abstract: We introduce wavelet analysis, an alternate signal processing method to Fourier analysis, to provide variables from scale morphology that discriminate among different spawning aggregations of fish. Fourier and wavelet analyses were used to transform averaged walleye (Sander vitreus) scale outline''s into shape variables. These variables violated the discriminant analysis’ assumption of multi-variate normality. Therefore, non-parametric statistics were used to assess the significance of the discriminant functions. Age-class effects were significant at one of the sampling locations, restricting all subsequent analyses by age-class. Variables from the wavelet decompositions formed significantly better discriminant functions than those based upon Fourier analysis for most comparisons. There was no detectable difference between the different orders of wavelets used to analyze the signals. [Copyright &y& Elsevier]

Examines the relationship between vessel behavior and resource distributions in commercial fisheries. Use of ideal free distribution (IFD); Form of competition between fishing vessels; Relationship between local catch rates and abundance and declines in smaller or weaker fish stocks; Advantages of IFD over other methods; Implications for commercial fisheries.

Describes the implementation of a course designed to require students to use their ecological knowledge on a local ecological problem. Overview of the course; Challenges in implementing the plan; Analysis of the course evaluations of students and professors; Proposed modifications to the project.

Arctic fishes are threatened by climatic change and other anthropogenic stressors, yet information on how such changes impact survival remains scarce. Acoustic telemetry has become valuable for studying aspects of fish ecology, including survival, which is invaluable in understanding potential responses to changing conditions. In Cambridge Bay, NU, we have been using acoustic telemetry to study movements and habitat use of the culturally and commercially important Arctic char (Salvelinus alpinus). Here, we combine acoustic telemetry data and Bayesian multistate mark–recapture models to study the survival of Arctic char from 2014 to 2018 in the region in freshwater and marine/estuarine habitats. We found that survival probabilities were high (>0.87) and models considering two environments (freshwater and marine) perform better than those considering three (including estuarine habitats). Furthermore, the survival in fresh water was higher than survival in marine/estuary environments. Overall, the results of this study further our understanding of important demographic parameters (i.e., survival) for Arctic char in the region, which will be useful in refining fishery management plans for the largest commercial fishery for this species in Canada. [ABSTRACT FROM AUTHOR]