Unanswered Forum Topics

Experiments on the use of sea bird mitigation methods were conducted aboard Uruguayan pelagic longliners between 2010 and 2012. Experiments looked at the difference between setting bait at the sea surface and setting baits underwater. The researchers recorded the abundance of sea birds following the vessel and incidences of attacks on bait and mortality. When the bait was set underwater, there was a marked reduction in the number of seabirds following the vessel and attacks on bait.

This research examined the spatial and temporal characteristics of pilot whale habitat use and longline fishing effort. The information was used to assess the potential for a spatial management approach to mitigate pilot whale bycatch. The Area Under the Curve and Williamson's Spatial Overlap Index were both used to assess patterns of overlap and bycatch by applying them to telemetry data from short-finned pilot whales, longline fishery effort and Pelagic Observer Program (POP) data (2014-2015).

The annual counts of large whale entanglements (including serious injury and mortalities) were analyzed and used to assess the effectiveness of the Atlantic Large Whale Take Reduction Plan. Fishing gear entanglements related to the annual number of mortality events averaged 2.5 for right whales (Eubalaena glacialis), 5.6 for humpback (Megaptera novaeangliae), 0.6 for fin whales (Balaenoptera physalus) and 2.4 for minke whales (B. acutorostrata).

A state-space model, using the Jolly-Seber assumption about population entry, was used to characterize the changing abundance of North Atlantic right whales (Eubalaena glacialis) between 1990 and 2015. Estimates from this modeling approach were only slightly higher than published values, except for the most recent years (capture rates substantially declined). North Atlantic right whale abundance increased about 2.8%/annually from the median estimate of 270 individuals in 1990 to 483 in 2010, followed by a decline to 458 in 2015.

Photographic data on body and skin condition, blowhole cyamids and rake marks were used to evaluate the health of North Atlantic right whales (Eubalaena glacialis) from 1980-2008. A hierarchical Bayesian model was applied to the data to estimate demographic groups, underlying health status conditions and the population to characterize health patterns and temporal trends. Visual health scores (0-100 scale) (N=48,560) were used to estimate the health of 622 identified right whales on a monthly basis. Most whales’ health scores fluctuated between 70 and 90.

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.