Abstract
North Atlantic right whales frequently become entangled in fishing gear,
which can negatively affect their reproductive output and probability
of survival. We estimated individual whale health from a hierarchical
Bayesian model fit to photographic indices of health. We reviewed 696
whales sighted from 1980 to 2011 and assigned 1196 entanglement events
to 573 individuals in six categories of increasing injury severity and
estimated monthly median health scores (0–100 scale) for the duration of
their life within the study period. We then quantified the relationship
between entanglement injury events and their severity with survival,
reproduction, and population health. Severe entanglements resulted in worse health for all whales—males and females with severe injuries were eight times more likely to die than males with minor injuries. Females with severe
injuries that survived had the lowest birth rates. Though the
relationship between entanglement and fecundity was complex, we found
that as the health of reproductively active females declined, their
calving intervals increased. Unimpacted whale health scores declined
significantly over three decades, 1980s, 1990s, and 2000s, suggesting
food limitations may be contributing to population-wide health declines.
Decadal health scores of entangled whales showed a more notable
reduction in health suggesting a clear and perhaps synergistic effect.
Original language | English |
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Article number | e12736 |
Number of pages | 14 |
Journal | Conservation Science and Practice |
Volume | 4 |
Issue number | 8 |
Early online date | 14 Jun 2022 |
DOIs | |
Publication status | Published - 1 Aug 2022 |
Keywords
- Entanglement
- Fixed fishing gear
- Health
- Injury severity
- Reproduction
- Survival