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1. Experimental demonstration of catch hyperstability from habitat aggregation, not effort sorting, in a recreational fishery

   https://doi.org/10.1139/cjfas-2019-0245  

   Dassow, Colin J.; Ross, Alexander J.; Jensen, Olaf P.; Sass, Greg G.; van Poorten, Brett T.; Solomon, Christopher T.; Jones, Stuart E. (April 2020, Canadian Journal of Fisheries and Aquatic Sciences)

   The relationship between angler catch rates and fish abundance can contribute to or hinder sustainable exploitation of fisheries depending on whether catch rates are proportional to fish abundance or are hyperstable. We performed a whole-ecosystem experiment in which fish abundance was manipulated and paired with weekly angler catch rate estimates from controlled experimental fishing. Catch rates were hyperstable (β = 0.47) in response to changes in fish abundance. By excluding effort sorting (i.e., catch rates remaining high because less skilled anglers leave the fishery as abundance declines), our experiment isolated the influence of fish aggregation as a driver of hyperstability. Spatial analysis of catch locations did not identify clustering around specific points, suggesting that loose aggregation to preferred habitat at the scale of the entire littoral zone was enough to maintain stable catch rates. In our study, general, non-spawning, habitat preferences created loose aggregations for anglers to target, which was sufficient to generate hyperstability. Habitat preferences are common to nearly all fishes and widely known to anglers, suggesting that many harvest-oriented recreational fisheries can be expected to exhibit hyperstability. 

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2. Juvenile social dynamics reflect adult reproductive strategies in bottlenose dolphins

   https://doi.org/10.1093/beheco/araa068  

   Galezo, Allison A; Foroughirad, Vivienne; Krzyszczyk, Ewa; Frère, Céline H; Mann, Janet (July 2020, Behavioral Ecology)

   Taborsky, Michael (Ed.)

   Abstract The juvenile period is a challenging life-history stage, especially in species with a high degree of fission–fusion dynamics, such as bottlenose dolphins, where maternal protection is virtually absent. Here, we examined how juvenile male and female bottlenose dolphins navigate this vulnerable period. Specifically, we examined their grouping patterns, activity budget, network dynamics, and social associations in the absence of adults. We found that juveniles live in highly dynamic groups, with group composition changing every 10 min on average. Groups were generally segregated by sex, and segregation was driven by same-sex preference rather than opposite-sex avoidance. Juveniles formed strong associations with select individuals, especially kin and same-sex partners, and both sexes formed cliques with their preferred partners. Sex-specific strategies in the juvenile period reflected adult reproductive strategies, in which the exploration of potential social partners may be more important for males (which form long-term alliances in adulthood) than females (which preferentially associate with kin in adulthood). Females spent more time alone and were more focused on foraging than males, but still formed close same-sex associations, especially with kin. Males cast a wider social net than females, with strong same-sex associations and many male associates. Males engaged in more affiliative behavior than females. These results are consistent with the social bonds and skills hypothesis and suggest that delayed sexual maturity in species with relational social complexity may allow individuals to assess potential associates and explore a complex social landscape without the risks associated with sexual maturity (e.g., adult reproductive competition; inbreeding). 

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3. Consequences of changing water clarity on the fish and fisheries of the Laurentian Great Lakes

   https://doi.org/10.1139/cjfas-2020-0376  

   Bunnell, David B.; Ludsin, Stuart A.; Knight, Roger L.; Rudstam, Lars G.; Williamson, Craig E.; Höök, Tomas O.; Collingsworth, Paris D.; Lesht, Barry M.; Barbiero, Richard P.; Scofield, Anne E.; et al (October 2021, Canadian Journal of Fisheries and Aquatic Sciences)

   Human-driven environmental change underlies recent changes in water clarity in many of the world’s great lakes, yet our understanding of the consequences of these changes on the fish and fisheries they support remains incomplete. Herein, we offer a framework to organize current knowledge, guide future research, and help fisheries managers understand how water clarity can affect their valued populations. Emphasizing Laurentian Great Lakes findings where possible, we describe how changing water clarity can directly affect fish populations and communities by altering exposure to ultraviolet radiation, foraging success, predation risk, reproductive behavior, or territoriality. We also discuss how changing water clarity can affect fisheries harvest and assessment through effects on fisher behavior and sampling efficiency (i.e., catchability). Finally, we discuss whether changing water clarity can affect understudied aspects of fishery performance, including economic and community benefits. We conclude by identifying generalized predictions and discuss their implications for priority research questions for the Laurentian Great Lakes. Even though the motivation for this work was regional, the breadth of the review and generality of the framework are readily transferable to other freshwater and marine habitats. 

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4. Diminishing productivity and hyperstable harvest in northern Wisconsin walleye fisheries

   https://doi.org/10.1139/cjfas-2023-0372  

   Mrnak, Joseph T; Embke, HS; Wilkinson, MV; Shaw, SL; Vander_Zanden, MJ; Sass, GG (December 2024, Canadian Journal of Fisheries and Aquatic Sciences)

   Managing fisheries in a changing socio-ecological environment may require holistic approaches for identifying and adapting to novel ecosystem dynamics. Using 32 years of Ceded Territory of Wisconsin (CTWI) walleye ( Sander vitreus) data, we estimated production ( P), biomass ( B), biomass turnover ( P/B), yield ( Y), and yield over production ( Y/P) and tested for hyperstability in walleye yield. Most CTWI walleye populations showed low P and B, and Y/P < 1 . Yet, production overharvest ( Y/P > 1) was prevalent among Wisconsin walleye recruitment-based management approaches (natural recruitment (NR), sustained only by stocking, combination). Production, B, and P/B have declined in NR populations, while Y and Y/P have remained constant. Walleye Y was hyperstable along a production gradient among all management approaches and fishery types (i.e., angling only, angling/tribal harvest combined). Diminishing productivity and hyperstable yield may be jointly contributing to observed walleye declines. We classified lakes into management groups of low, moderate, or high vulnerability to harvest based on Y/P and P/B dynamics and identify that harvest may benefit from declines to maintain or increase the adaptive capacity of CTWI walleye. 

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5. Female choice and sexual coercion in wild orangutans (Pongo pygmaeus wurmbii)

   Scott, AM; Susanto, TW; Knott, CD (January 2021, 90th Annual Meeting of the American Association of Physical Anthropologists)

   null (Ed.)

   Due to extreme incongruence in parental investment, the potential for sexual conflict in orangutan reproductive strategies is high. Female orangutans prefer flanged males, but with intense male-male competition and sexual coercion, it is unclear how females are able to exert choice. We hypothesized that female orangutans use initiation and maintenance of associations with preferred males as a mechanism of female choice. We used encounter rates and behavioral measures of proximity maintenance to distinguish between the role of female choice and male coercion in male-female associations in Gunung Palung National Park, West Kalimantan, Indonesia. From May 2018-April 2019, we collected data on initiation, termination, and proximity maintenance during associations between males and cycling females (females without dependent offspring or with offspring over 6 years old). Encounters between cycling females and flanged males were more likely to be female-initiated (83.3%), while encounters with unflanged males were more likely to be male-initiated (80%) (N=16, p=0.035, Fisher’s exact test). Additionally, the Brown Index indicates significantly more female proximity maintenance when cycling females associated with flanged males than unflanged males (N=33, W = 198.5, p= 0.012). However, using long-term data on male-female associations, we found that dyads of flanged males and females were less likely to encounter other males compared to dyads of unflanged males and females (N=542, χ2= 3.3051, df=1, p=0.035). This indicates that flanged males may also use associations to mate guard females. These data indicate that there are behavioral manifestations of both female choice and male coercion in orangutan associations. Funders: NSF (DGE-1247312, BCS-1638823, BCS-0936199), Boston University, Leakey Foundation, Disney Conservation Fund, and US Fish and Wildlife Service (F18AP00898) 

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