Confusion Over 60 to 80% Whale Injury Reduction Rate Clarified
Following the release of the notice below to Atlantic Large Whale Take Reduction Team members on April 05, 2019 rumors circulated in some quarters regarding what the reduction percentages were referring to. The relevant text of the notice released by NOAA Fisheries appears in full below.
To: TRT Members and Alternates
Throughout the past year, as we’ve met to discuss modifications to the Atlantic Large Whale Take Reduction Plan, NMFS has consistently stressed that significant changes will be needed to achieve the Marine Mammal Protection Act (MMPA) goal of reducing mortality and serious injury (M/SI) below the North Atlantic right whale Potential Biological Removal (PBR) level of 0.9. As explained below, we believe that to achieve this goal, mortalities and serious injuries in U.S. fisheries will likely need to be reduced by 60 to 80% from current levels.
As you all know, despite two decades of the Take Reduction Team’s efforts, right whale entanglement mortalities and serious injuries continue to exceed PBR. The modest upward trajectory of the population through the early 2000s appears to have reversed since 2010. This downward trend, exacerbated by unprecedented mortalities (particularly in the Gulf of St. Lawrence snow crab fishery) in 2017, lends a new urgency to the Take Reduction Team’s continued collaboration to modify the Plan to get M/SI below PBR.
Identifying our take reduction target
The draft 2018 North Atlantic right whale stock assessment establishes a PBR level of 0.9 right whales a year based on 2016 population estimates. The report documents a minimum rate of average annual right whale mortalities and serious injuries caused by entanglements over the five-year period from 2012 to 2016 as 5.15 whales per year. An annual average of 0.4 of these mortalities and serious injuries were attributed to U.S. fisheries and 0.4 mortalities per year were attributed to Canadian fisheries; 4.4 of the documented mortalities and serious injuries could not be attributed to a fishery in either country. Since the draft report was published, an additional mortality may have been attributed to Canadian snow crab gear: under this assumption, 4.2 remain unattributed.
Although right whales spend more time exposed to fisheries in U.S. waters than in Canadian waters, for the purposes of guiding the development of take reduction measures, we are making an assumption that 50% of right whale mortalities and serious injuries occur in each country. This assumption is supported by the analysis of recovered entangling gear. The heavy traps and large diameter high breaking strength lines used to target snow crabs in Canada are more lethal than most U.S. fishing gear. Additionally, take reduction measures implemented in U.S. fisheries over the past two decades have reduced the impacts of U.S. fisheries.
Under this assumption, for the period between 2012 and 2016, an annual average of up to 2.5 - 2.6 mortalities and serious injuries are attributed to U.S. fisheries, more than 2.5 times greater than PBR. Reducing mortality and serious injury by at least 60% in U.S. fisheries would likely be needed to get below the PBR level of 0.9.
These numbers include only documented mortalities and serious injuries. Actual mortalities and serious injuries of right whales in U.S. fisheries are likely higher than the observed 2.6 per year. Population models provide an estimate of mortalities that suggest that 60% of right whale mortalities and serious injuries are unobserved (Pace, personal communication applying the methods from Pace et al. 2017). If the average observed mortalities and serious injuries caused by entanglements for 2012 through 2016 is 5.15, given the 60% detection rate, the estimated annual mortality and serious injury by entanglements is 8.6 per year. If we assume half of the estimated mortalities and serious injuries occur incidental to U.S. fisheries (4.3), mortality and serious injury would have to be reduced by about 80% in U.S. fisheries to get below the stock’s PBR of 0.9.
Canada implemented static and dynamic closures in 2018 that appeared to effectively prevent mortalities in the Gulf of St. Lawrence trap/pot fisheries last year. They have announced more focused measures in 2019 that we hope will be similarly successful. NMFS will continue to collaborate with Canada through ongoing bilateral discussions to ensure sustained take reduction efforts throughout the right whale’s range.
We know this target is daunting, but it is necessary to ensure the recovery of the North Atlantic right whale population. We hope that your creative ideas and willingness to continue to collaborate with each other at our upcoming meeting will generate recommended measures that will be meaningful to the population’s recovery and manageable for the fishing industry. We remain committed to working closely with you throughout this process.