First estimates of entanglement rate of humpback whales Megaptera novaeangliae observed in coastal Icelandic waters

Basran, Charla J.; Bertulli, Chiara G.; Cecchetti, Arianna; Rasmussen, Marianne H.; Whittaker, Megan; Robbins, Jooke

doi:10.3354/esr00936

Cited by 21 publications

(20 citation statements)

References 35 publications

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“…A sighting in June of that year revealed that Spinnaker had unhealed injuries from a recent, unreported entanglement, but the injuries were similar in nature and severity to those routinely documented among free-swimming whales in this population (e.g. Robbins and Mattila, 2001 ; Robbins, 2012 ) and others ( Neilson et al , 2009 ; Basran et al, 2019 ; Ramp et al, 2021 ). Although her corticosterone levels were still much higher than the other whales, her average cortisol (1.505 ng/g) was comparable to SEAK 68 (1.844 ng/g, ship strike death) and SEAK 441 (1.618 ng/g, chronic illness; Fig.…”

Section: Resultsmentioning

confidence: 79%

Patterns of cortisol and corticosterone concentrations in humpback whale (Megaptera novaeangliae) baleen are associated with different causes of death

Lowe

Hunt

Robbins

et al. 2021

Conservation Physiology

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Baleen whales are subject to a myriad of natural and anthropogenic stressors, but understanding how these stressors affect physiology is difficult. Measurement of adrenal glucocorticoid (GC) hormones involved in the vertebrate stress response (cortisol and corticosterone) in baleen could help fill this data gap. Baleen analysis is a powerful tool, allowing for a retrospective re-creation of multiple years of GC hormone concentrations at approximately a monthly resolution. We hypothesized that whales that died from acute causes (e.g. ship strike) would have lower levels of baleen GCs than whales that died from extended illness or injury (e.g. long-term entanglement in fishing gear). To test this hypothesis, we extracted hormones from baleen plates of four humpback whales (Megaptera novaeangliae) with well-documented deaths including multiple and chronic entanglements (n = 1, female), ship strike (n = 2, male and female) and chronic illness with nutritional stress (n = 1, male). Over ~3 years of baleen growth and during multiple entanglements, the entangled whale had average corticosterone levels of 80–187% higher than the other three whales but cortisol levels were similar to two of the other three whales. The nutritionally stressed and chronically ill whale showed a slow increase in both cortisol and corticosterone spanning ~3 years, followed by a sharp decline in both hormones before death, possibly indicative of adrenal failure in this moribund individual. This whale’s correlation between cortisol and corticosterone was significant but there were no correlations in the other three whales. Our results show that cortisol and corticosterone concentrations vary according to the type and duration of illness or injury. Single-point GC concentrations should be interpreted with caution as low values can occur in whales experiencing pronounced stress and individual baselines can be highly variable. Baleen analysis is a promising tissue type for retrospective analyses of physiological responses to various stressors affecting baleen whales.

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Section: Resultsmentioning

confidence: 79%

Patterns of cortisol and corticosterone concentrations in humpback whale (Megaptera novaeangliae) baleen are associated with different causes of death

Lowe

Hunt

Robbins

et al. 2021

Conservation Physiology

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“…This is particularly true for pot/trap and gillnet gears which are left in the water, unattended, for longer periods of time and are well known for entangling whales (Johnson et al, 2005). For example, in Iceland, a study based on scarring estimated that a minimum of 25% of humpback whales have been entangled previously (Basran et al, 2019) and additionally 15% of questionnaire respondents witnessed humpback whales interact with their fishing gear (Basran and Rasmussen, 2021). Furthermore, there have been reports of humpback whale deaths due to entanglement in interviews with fishing vessel captains (Basran and Rasmussen, 2021), and based on examination of stranded animals (Víkingsson et al, , 2005Víkingsson, 2011).…”

Section: Discussionmentioning

confidence: 99%

Using Case Studies to Investigate Cetacean Bycatch/Interaction Under-Reporting in Countries With Reporting Legislation

Basran

Sigurðsson

2021

Front. Mar. Sci.

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Accurate reporting of cetacean bycatch in/interaction with fishing gear in fisher logbooks would be of immense scientific value; however, despite some countries having mandatory reporting laws, logbook reporting is widely considered unreliable and cetacean catches are thought to be under-reported. Despite this widespread notion of logbook unreliability, under-reporting has rarely been quantified. For this study, initially we compiled the first comprehensive legislation summary for countries which have cetacean bycatch/interaction reporting laws. We then used data provided by government and research agencies in three case study countries (New Zealand, United States, and Iceland) to test for differences between logbook and observer reported cetacean bycatch. Comparisons were made using paired t-tests and Wilcoxon tests with a set alpha of 0.05. Overall, cetacean bycatch recorded by observers was higher than that from fisher logbooks by an average of 774% in trawls, 7348% in nets, and 1725% in hook and line gears. When combining all years of data available, fisher logbook cetacean catch per unit efforts or average number of individuals caught were significantly less than those from observer data for all gear types that could be examined in all countries, except for lining in New Zealand. Overall, there was significant under-reporting in the case study countries despite differences in geographic location, cetacean species and density and EEZ size, suggesting these results would likely be similar in many countries with comparable, well-developed fishing industries. Under-reporting in logbooks, despite laws, was clearly quantified and it is known that fishers have little incentive to report and have concerns over negative repercussions to the industry over bycatch issues. If logbook reporting is to continue in some fisheries, clearer legislation, simplified reporting using new technology (such as smartphone apps) and combination with electronic monitoring cameras to verify compliance may improve reporting accuracy. The introduction of electronic monitoring, given its lower cost compared to observer programs and high accuracy, may be the most viable option to obtain reliable cetacean bycatch estimates, and could be considered to replace logbook reporting altogether.

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“…Interactions between whales and gear also causes financial loss to fisheries in terms of gear damage, down-time for repairs and loss of catch (Lien, 1979;Lien and Aldrich, 1982), particularly large whale interactions such as humpback whales. For humpback whales, it is estimated that the studied populations in Iceland, the Gulf of Maine, and Alaska are entangled in fishing gear at a rate of 2%, 14-17% and 8% per year respectively (Basran et al, 2019;Robbins, 2012;Neilson et al, 2009). Possibly due to the concern over negative consequences for the fishing industry, under-reporting of bycatch and interactions with large marine mammals is common (e.g.…”

Section: Introductionmentioning

confidence: 99%

Fishers and whales in Iceland

Basran¹,

Rasmussen²

2022

JCRM

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In Iceland, as in many places globally, the detrimental impacts of whale interactions with fishing gear on both fisheries and whales are not well understood and managed. This study conducted anonymous questionnaires of Icelandic fishers and interviews of capelin purse seine boat captains to gather first-hand knowledge of the issues fishers face due to whale interaction with their fishing gear. Results suggest that the humpback whale is the large whale species that is most often entangled or encircled in fishing gear and causing damage, however on occasion other large whale species are interacting with gear as well. Interactions between humpback whales and fishing gear appears to be primarily concentrated in the north/northeast and southwest of the country where there is high fishing effort and known humpback whale feeding habitat. Humpback whale interactions with gear occurred most often with capelin purse seines, which are targeting humpback whale prey, and data suggests that bycatch of whales in this fishery may be underreported. Damage and losses due to whale collisions with gear were reported to cost fishers up to 55.000.000ISK, suggesting this can be a costly issue for which mitigation measures should be explored. The use of acoustic â€œpingersâ€ is one mitigation measure that has been previously tested by capelin purse-seiners and is something that captains indicated they would be interested in continuing to try. The creation of a whale entanglement/whale-gear interaction reporting system in Iceland would aid in gathering more data and quantifying how often these events are witnessed and what the consequences of these events are to both the fishers and the whales. This study provides new information about the consequences of large whale interactions with Icelandic fisheries and suggests that future collaboration with fishers can provide insight contributing to best management practices for sustainable fishing and whale conservation.

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First estimates of entanglement rate of humpback whales Megaptera novaeangliae observed in coastal Icelandic waters

Abstract: hundreds of thousands of individuals (Read et al. 2006). Most types of fishing gear (e.g. gillnets, long lines, and pot/trap lines) are known to cause entanglements (

Cited by 21 publications

References 35 publications

Patterns of cortisol and corticosterone concentrations in humpback whale (Megaptera novaeangliae) baleen are associated with different causes of death

Patterns of cortisol and corticosterone concentrations in humpback whale (Megaptera novaeangliae) baleen are associated with different causes of death

Using Case Studies to Investigate Cetacean Bycatch/Interaction Under-Reporting in Countries With Reporting Legislation

Fishers and whales in Iceland

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