The Danger Of Fishing Gear For Right Whales
Here at Faunalytics, we’ve covered issues affecting right whales, including stress related to ship noise, as well as the potential for marine spatial planning (MSP) to provide some kind of protection for the species. Now, we turn our attention to the danger of fishing gear for right whales, and the potential for these huge animals to become entangled in it. Entanglement in fishing gear has been identified as a potential conservation concern for baleen whales around the world, and researchers are now looking at North Atlantic right whales to see if they might also be threatened by it. The North Atlantic right whale is an endangered species that is thought to only number around 500 individuals, making it a species of particular concern. Since 1970, at least 122 deaths of right whales have been recorded and at least 57% of those were the result of human activities.
This paper delves into the topic of entanglement death for right whales, noting that they “are known to interact with fishing gear frequently,” but that the actual impacts to individuals and populations “are not well understood.” The authors say that measuring entanglement with precision is a difficult process because so much of it remains a hidden phenomenon. While we know entanglement happens, and we know that right whales die from it, “there can be uncertainty about entanglement outcome because survivors are not necessarily re-sighted and deaths are not necessarily witnessed.” To try to better understand this phenomenon, the researchers say there is now a “formal entanglement reporting network” to detect and respond to entangled whales. Using certain identification techniques, it is possible to track whales and re-sight them if they survive. Using “single and multi-state mark recapture models,” the researchers here set out to estimate the survival rate of right whales after reported and properly documented entanglements.
The researchers found that, between 1980 and 2009, 62 “adequately-marked” whales were involved in 66 reported entanglements and that the researchers “focused on 50 individuals involved in 53 events between 1995 and 2008, and potentially re-sighted through 2009.” Interestingly, the sample included an almost equal number of males and females, and an almost even split of mature whales and juveniles. Eight of the entanglements were known to result in deaths because the bodies were recovered. Nine of the incidents were inconclusive because the whales had not been re-sighted and those individuals had been missing for periods of time ranging from 1-11 years. The remaining 36 cases “involved individuals that were re-sighted in at least one year after gear was shed or removed, but were not necessarily known to be alive by the end of the study period.” The researchers made a special note that the “vast majority (81%) of cases” were categorized as having “high risk gear configurations.” In only 40% of cases did the right whales successfully disentangle themselves.
The paper synthesizes previously gathered data and puts into perspective the danger of fishing gear for right whales. The researchers say the results are significant and indicate “that both juveniles and adults have a lower probability of survival after a reported entanglement.” Overall, right whales that have been entangled in fishing gear have about a 25% lower chance of survival than those that haven’t been. They note that “this is the first estimate of survival reduction relative to unaffected animals and sets a baseline against which to evaluate the success of future mitigation efforts.” That said, they are also careful to note that this study only covers reported and documented entanglements; the actual threat to right whales could be much higher. For wild animal advocates, this new information shows a clear intersection between fishing, the consumption of fish, and wild animal protection. While right whales are not hunted for human consumption, fishing gear poses a threat too, and this intersection feels especially acute for endangered species.