Search The Database

North Atlantic right whale (Eubalaena glacialis) survey data and Canadian fishing gear deployment data were used to estimate the threat of gear entanglement to right whales in the Scotia-Fundy region and the risk of lethal entanglement in the Bay of Fundy and Roseway Basin, Scotian Shelf. The following fisheries were investigated: groundfish and pelagic hook and line, groundfish gillnet, and crab, hagfish and inshore/offshore lobster traps. Groundfish hook and line gear poses the largest threat to right whales during the summer resident period in the Bay of Funday and on Roseway Basin (critical habitat). The lobster fishery poses the greatest threat during the spring and summer periods as whales migrate to and from Critical Habitat. Gillnets pose a considerable gear related threat, 18% of the total threat. 

North Atlantic right whale (Eubalaena glacialis) survey data and Canadian fishing gear deployment data were used to estimate the threat of gear entanglement to right whales in the Scotia-Fundy region and the risk of lethal entanglement in the Bay of Fundy and Roseway Basin, Scotian Shelf. The following fisheries were investigated: groundfish and pelagic hook and line, groundfish gillnet, and crab, hagfish and inshore/offshore lobster traps. Groundfish hook and line gear poses the largest threat to right whales during the summer resident period in the Bay of Funday and on Roseway Basin (critical habitat). The lobster fishery poses the greatest threat during the spring and summer periods as whales migrate to and from Critical Habitat. Gillnets pose a considerable gear related threat, 18% of the total threat. 

North Atlantic right whale (Eubalaena glacialis) survey data and Canadian fishing gear deployment data were used to estimate the threat of gear entanglement to right whales in the Scotia-Fundy region and the risk of lethal entanglement in the Bay of Fundy and Roseway Basin, Scotian Shelf. The following fisheries were investigated: groundfish and pelagic hook and line, groundfish gillnet, and crab, hagfish and inshore/offshore lobster traps. Groundfish hook and line gear poses the largest threat to right whales during the summer resident period in the Bay of Funday and on Roseway Basin (critical habitat). The lobster fishery poses the greatest threat during the spring and summer periods as whales migrate to and from Critical Habitat. Gillnets pose a considerable gear related threat, 18% of the total threat. 

Two test systems were developed to examine fishing line entanglement injuries in humpback (Megaptera novaeangliae) and North Atlantic right whale (Eubalaena glacialis). The systems evaluated straight pull abrasion and oscillatory abrasion in relation to tissue compliance. The straight pull abrasion study was used to measure the depth of epidermal penetration after a unidirectional pull of line over a standard draw-length. The oscillatory pull abrasion system measured the tissue compliance limit under a shear load and used a series of upper/lower pulleys to position an abrading line across the leading edge of the test sample. Tissues from the leading edge of a flipper for a right whale calf and leading edge of an adult right whale were used during this study. Line furrow patterns were documented through photographs and tissue abrasion was compared using the 1) maximum depth of epidermal/dermal penetration and 2) length of epidermal removal. For the straight pull abrasion test, an adult right whale fluke required 3.7 times the load and 15 times the draw-length of a right whale calf flipper for epidermal failure to occur. The oscillatory abrasion test indicated that line draw-lengths were more than the tissue compliance limit and resulted in substantial increased tissue abrasion. Increasing the line's ability to stretch in response to a load could minimize sliding of the line and help mitigate entanglement injuries.

Fishery data collected from the Reunion Island and Seychelles pelagic longline fisheries (targeting swordfish and tuna) between 2004 and 2015 was used to propose depredation indicators and to assess depredation levels in these fisheries. The interaction rate (depredation) was significantly higher for sharks compared to toothed whales in both fisheries. However, there was a higher depredation per unit effort from toothed whales compared to sharks indicating the impact was more significant. The gross depredation rate in the Seychelles fishery was 18.3%. A slight increase in the gross depredation rate was seen over time in the Reunion Islands fishery (4.1% 2007-2010 and 4.4% in 2011-2015). These indicators were used to estimate the economic loss to these fisheries from depredation events. For the Reunion Island fishery the economic loss was 0.09 EUR/hook and 0.86 EUR/hook for the Seychelles. The results suggest a southward decreasing tooth whale and shark depredation gradient. The depredation levels in the Seychelles are some of the highest in the world and may suggest a 'hot spot' of interactions between toothed whales and pelagic longlines.

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). Annual entanglement rates increased during the study period (1999-2009), increased rates of entanglement-related mortality were equivocal. There were no significant changes in waiting time in response to any management measures implemented to reduce large whale mortalities between 1999 and 2009. This implies the measures were generally ineffective.

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. There is evidence of diverging abundance trends between sexes, a result of reduced survival of females.

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. Whales in poor condition had health scores >60. Health varied by sex, age-class and reproductive state. The largest annual variability was observed in active reproducing females. Calving females had significantly higher health scores than non-calving females. Population health declined and coincided with a decrease in calving from 1998-2000. Over three generations the health in all demographic groups declined.

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 versus 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.

This study evaluated drag characteristics of entangled North Atlantic right whales (Eubalaena glacialis), 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. Reducing trailing line length by 75% can reduce parasitic gear drag by 85%.