Unanswered Forum Topics

The fecal glucocorticoid metabolites (fGC) concentrations from right whales (Eubalaena glacialis) chronically entangled in fishing gears or live stranded were compared to right whales quickly killed by vessels and healthy right whales. The study aimed to characterize fGC responses to acute vs. chronic stress. fGCs in entangled whales and stranded whales were significantly higher than in whales killed by vessels and healthy whales. Serum cortisol and corticosterone in a live stranded whale were much higher than values reported in other cetaceans.

The kinematics of a tagged entangled North Atlantic right whale, before, during and after disentanglement were examined. Three sets of gear attached to a load-cell tensiometer at multiple speeds were used to calculate additional drag forces and energetic demand. Tag analyses revealed significant increases in dive depths and duration; ascent, descent and fluke stroke rates; and decreases in rot mean square fluke amplitude were significantly greater than in the non-entangled case.

This study evaluated drag characteristics of entangled North Atlantic right whales, contextualized gear drag measurements for individual whales and quantified the benefits of partial disentanglement. A load cell was used to measure drag forces on 15 sets of fishing gear removed from entangled right whales, a towed satellite telemetry buoy and 200 m of polypropylene line as it was shored to 25 m, as they were towed behind a vessel at -0.77, 1.3 and 2.1 m/s and 0, 3 and 6 m depth. Information suggests that on average entanglements increase drag and propulsive power by 1.47 fold.

Standardized external injury assessments were used to investigate the relative importance of direct anthropogenic and natural threats to northwest Atlantic leatherback turtles (Dermochelys coriacea). The information was used to assess whether the susceptibility to these threats varies between low latitude nesting and high latitude foraging region, by size and sex. Leatherback turtles foraging off the coast of Nova Scotia and at nesting sites in Trinidad were sampled. Combined, 62% showed characteristic marking associated with one injury.

The effects of hook soak time on targeted reef fish and shark bycatch were investigated in the eastern Gulf of Mexico bottom longline fishery. Hook timers were used to evaluate capture time and catch per unit effort (CPUE) for the target species, red grouper (Epinephelus morio). The results indicate the typical duration of hook soak times is longer than needed to efficiently harvest red grouper. Reducing soak time to less than one hour would result in minimal to no reduction and CPUE of red grouper.

The effects of hook soak time on targeted reef fish and shark bycatch were investigated in the eastern Gulf of Mexico bottom longline fishery. Hook timers were used to evaluate capture time and catch per unit effort (CPUE) for the target species, red grouper (Epinephelus morio). The results indicate the typical duration of hook soak times is longer than needed to efficiently harvest red grouper. Reducing soak time to less than one hour would result in minimal to no reduction and CPUE of red grouper.

Key pelagic shark species are caught in the North Pacific by Japanese longline fisheries as bycatch. These species include blue shark (Prionace glauca) and shortfin mako (Isurus oxyrinchus). In this study, fishery-independent data was leveraged by utilizing a generalized linear mixed model to standardize these data and identify changes in spatio-temporal catch rates. For blue shark, catch was recorded from temperate waters of the western and central North Pacific.

Direct interactions between longline fisheries and many top predators such as toothed whales result in substatial impacts on fishing activity; depredating species and fish stocks. These issues continue to be a growing concern in fisheries worldwide, including the French Patagonian toothfish fishery. In this field study, researchers deployed data loggers on killer whales and sperm whales while aboard commercial toothfish demersal longline fishing vessels to gain insight into when, where and how depredation occurs.

In 2015, NPF Industry Pty Ltd launched the Northern Prawn Fishery’s Bycatch Strategy 2015-2018 with the vision to reduce small bycatch by 30% in three years. A key component of the strategy was industry innovation and through this process the Kon’s Covered Fisheyes Bycatch Reduction Device (BRD) was developed.In 2016, at-sea testing of the Kon’s Covered Fisheyes Bycatch Reduction Device (BRD) was conducted in the Gulf of Carpentaria to determine its effectiveness in reducing small bycatch in the tiger prawn fishery compared to a currently legislated device.

Mobulid rays are distributed worldwide in tropical and warm temperate waters, and are landed as bycatch in many different fisheries. Five mobulid species (Mobula birostris, M. japanica, M.munkiana, M.