Volunteer Angling and Technology-Based Solutions Provide the First Estimate of Sea Lice Infections for Wild Coastal Cutthroat Trout (Oncorhynchus Clarkii Clarkii)

Anadromous Coastal Cutthroat Trout Oncorhynchus clarkii clarkii are one of the least studied salmonids but are a highly prized target in sport fisheries in coastal waters of the Pacific Northwest. Despite an observed high prevalence of ectoparasite infections, described by sport anglers as "sea lice," there is a paucity of data available on the spatial and temporal occurrence of infections on Coastal Cutthroat Trout. We collaborated with the angling community through social media engagement and an online application to report ectoparasites observed on sport catch. In 2018, we received voluntary reports for 1,493 Cutthroat Trout and 416 salmon catch events in marine waters from the province of British Columbia and the states of Washington, Oregon, and California. These data demonstrated that the number of argulids and copepods per trout varied according to body size, capture month, and area. To evaluate accuracy of voluntary parasite counts, we compared results to parasite counts on cutthroat from sampling events conducted by trained biologists. For both voluntary angler reports and those of biologists, spring months had a lower prevalence of argulids and copepods, argulids were common on trout, but absent on salmon, and larger trout were associated with an increased number of argulid and copepod infections

Using Logbook Data to Determine the Immediate Mortality of Blue Sharks (Prionace glauca) and Tiger Sharks (Galeocerdo cuvier) Caught in the Commercial U.S. Pelagic Longline Fishery

Commercial fisheries are recognized as one of the greatest threats to shark populations worldwide, but factors affecting the likelihood of shark mortality during fishery capture are poorly understood. We used the U.S. pelagic fishery logbook data from 1992 through 2008 to quantify the effects of several variables (fisheries regulatory periods, geographic zone, target catch, and sea surface temperature) on mortality of blue sharks (Prionace glauca) and tiger sharks (Galeocerdo cuvier). Mortality rates and trends in both species closely matched those recorded from other sources, and therefore indicated that the data on sharks discarded dead and discarded alive in the U.S. pelagic fishery logbook are accurate. The introduction of fisheries management regulations (fin weight to carcass weight ratios in 1993 [to prevent finning] and the prohibition of J-hooks in 2004) presumably decreased the immediate mortality rate of captured blue and tiger sharks (by 8.0% in blue sharks after 2004 and 4.4% in tiger sharks after 1993). Other factors that we examined had a statistically significant effect on mortality, but additional variables should be recorded or made available in logbook data to enable the determination of other causes of mortality. Our results show that the U.S. pelagic fishery logbook data can be used as a powerful tool in future studies of the immediate mortality of longline-caught animals

Moving from Measuring to Predicting Bycatch Mortality: Predicting the Capture Condition of a Longline-Caught Pelagic Shark

Incidental fisheries capture has been identified as having a major effect on shark populations throughout the world. However, factors that contribute to the mortality of shark bycatch during fisheries capture are not fully understood. Here, we investigated the effects of capture duration, sea surface temperature, and shark total length (snout to the tip of the upper caudal lobe) on the physiology and condition of longline-caught bronze whalers, Carcharhinus brachyurus. Plasma lactate and potassium concentration had a positive linear relationship with capture duration, indicating that this species experiences increasing physiological challenges while on fishing gear. Additionally, we used stereotype logistic regression models to determine variables that could predict the capture condition of sharks (categorized as healthy, sluggish, or moribund or dead). In these models, elevated plasma lactate concentration, plasma potassium concentration, and capture duration increased the likelihood of C. brachyurus being captured in a sluggish condition or in a moribund or dead condition. After plasma lactate concentration exceeded 27.4 mmol/L, plasma potassium concentration exceeded 8.3 mmol/L, or capture durations exceeded 293 minutes, the majority of captured sharks (>50%) were predicted to be moribund or dead. We recommend that a reduction in the amount of time longlines are left fishing (soak time) will reduce immediate and post-release mortality in C. brachyurus bycatch and that our methods could be applied to identify causes of fisheries-induced mortality in future studies. The identification of operational, environmental, and biological variables contributing to poor condition will be necessary to implement conservation strategies that reduce mortality during capture

Ecological vulnerability of the chondrichthyan fauna of southern Australia to the stressors of climate change, fishing and other anthropogenic hazards

We develop a potentially widely applicable framework for analysing the vulnerability, resilience risk and exposure of chondrichthyan species to all types of anthropogenic stressors in the marine environment. The approach combines the three components of widely applied vulnerability analysis (exposure, sensitivity and adaptability) (ESA) with three components (exposure, susceptibility and productivity) (ESP) of our adaptation of productivity–susceptibility analysis (PSA). We apply our 12-step ESA‒ESP analysis to evaluate the vulnerability (risk of a marked reduction of the population) of each of 132 chondrichthyan species in the Exclusive Economic Zone of southern Australia. The vul nerability relates to a species’ resilience to a spatial (or suitability) reduction of its habitats from exposure to up to eight climate change stressors. Vulnerability also relates to anthro pogenic mortality added to natural mortality from exposure to the stressors of five types of fishing and seven other types of anthropogenic hazards. We use biological attributes as risk factors to evaluate risk related to resilience at the species or higher taxonomic level. We evaluate each species’ exposure to anthropogenic stressors by assigning it to one of six ecological groups based on its lifestyle (demersal versus pelagic) and habitat, defined by bathymetric range and substrates. We evaluate vulnerability for 11 scenarios: 2000– 2006 when fishing effort peaked; 2018 following a decade of fisheries management reforms; low, medium and high standard future carbon dioxide equivalent emissions sce narios; and their six possible climate–fishing combinations. Our results demonstrate the value of refugia from fishing and how climate change exacerbates the risks from fishing.Fil: Walker, Terence I.. Monash University; Australia. The University of Melbourne; AustraliaFil: Day, Robert W.. The University of Melbourne; AustraliaFil: Awruch, Cynthia Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. University of Tasmania; AustraliaFil: Bell, Justin D.. Institute For Marine And Antarctic Studies; AustraliaFil: Braccini, Juan Matias. Wa Fisheries And Marine Research Laboratories; AustraliaFil: Dapp, Derek R.. Monash University; AustraliaFil: Finotto, Licia. Monash University; AustraliaFil: Frick, Lorenz H.. Monash University; AustraliaFil: Garcés-García, Karla C.. Universidad Veracruzana; México. The University of Melbourne; AustraliaFil: Guida, Leonardo. Monash University; AustraliaFil: Huveneers, Charlie. Flinders University; AustraliaFil: Martins, Camila L.. Monash University; AustraliaFil: Rochowski, Bastien E.A.. The University of Melbourne; AustraliaFil: Tovar-Ávila, Javier. Inapesca; MéxicoFil: Trinnie, Fabian I.. Wa Fisheries And Marine Research Laboratories; AustraliaFil: Reina, Richard D.. Monash University; Australi