Abundance, food habits, and annual fish consumption of California sea lion (Zalophus californianus) and its impact on salmonid fisheries in Monterey Bay, California

Weise, Michael; Eguchi, Tomoharu; Orr, Tony; Alisea, Tony; Henkel, Laird A.; Oates, Stori C.; Bizarro, Joe; Neer, Julie A.; Benson, Scott R.; Greig, Denise J.; Parra, G. I. Rivera; Reyes, Mimi; Cunningham, G.; Updike, Sharon; Garcia, Michelle; Harrell, Jack

doi:10.31979/etd.ut2v-j72k

Cited by 10 publications

(12 citation statements)

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“…), provide a foundation for the first species‐specific population growth model for California sea lions. The development of such a model is needed to inform management on a species that has been at the center of resource conflicts in parts of its range ( e.g ., Weise and Harvey , Wright et al . ) and also faces a challenging future.…”

Section: Discussionmentioning

confidence: 99%

Age‐ and sex‐specific survival of California sea lions (Zalophus californianus) at San Miguel Island, California

DeLong

Melin

Laake

et al. 2017

Marine Mammal Science

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We conducted a mark‐recapture study of California sea lions (Zalophus californianus) using pups branded on San Miguel Island, California, from 1987 to 2014, and annual resightings from 1990 to 2015. We used the Burnham model (Burnham 1993), an extension of the Cormack‐Jolly‐Seber mark‐recapture model, which includes recoveries of dead animals, to analyze age, sex, and annual patterns in survival. Generally, females had higher survival than males. For female pups, the average annual survival was 0.600 and for male pups it was 0.574. Yearling survival was 0.758 and 0.757 for females and males, respectively. Peak annual survival was at age 5 and was 0.952 for females and 0.931 for males. Pups with larger mass at branding had higher survival as pups and yearlings, but the effect was relative within each cohort because of large between‐cohort variability in survival. Annual variability in sea surface temperature (SST) affected survival. For each 1°C increase in SST, the odds of survival decreased by nearly 50% for pups and yearlings; negative SST anomalies yielded higher survival. Annual variation in male survival was partly explained by leptospirosis outbreaks. Our study provides a unique view of one demographic parameter that contributed to the successful recovery of the California sea lion population.

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Section: Discussionmentioning

confidence: 99%

Age‐ and sex‐specific survival of California sea lions (Zalophus californianus) at San Miguel Island, California

DeLong

Melin

Laake

et al. 2017

Marine Mammal Science

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“…Percentage mass for market squid, rockfishes, sardine, and anchovy identified and reconstructed from sea lion fecal samples collected on Año Nuevo Island from 2002 to 2005 [ Weise , 2006], and fecal samples collected by Weise [2000] and M. J. Weise and J. Harvey (unpublished data, 1999) in the Monterey Bay from 1997 to 1999. Dashed lines highlight the 1997–1998 El Niño event and similar changes during 2004–2005.…”

Section: Discussionmentioning

confidence: 99%

Movement and diving behavior of male California sea lion (Zalophus californianus) during anomalous oceanographic conditions of 2005 compared to those of 2004

Weise

Costa

Kudela

2006

Geophysical Research Letters

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[1] During the highly anomalous conditions in early 2005, characterized by increased water temperatures and decreased productivity, male California sea lions adopted previously undocumented foraging behaviors. We investigated the movement and spatially explicit foraging behavior of males using satellite-linked data loggers and compared foraging behavior and effort between 2003 -2004 and 2004 -2005 Lett., 33, L22S10,

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“…Predation is a crucial factor in any fishery where fish are held vulnerable for extended periods. For example, in hook fisheries, fish dragged behind trolling vessels are exposed to highly mobile predators (Weise & Harvey, ; Zollett & Read, ) and the passive counterpart, longlines, can be deployed for long periods of time, holding fish vulnerable to a number of predators (Nishida & Shiba, ). Fish held captive in hanging nets can also be highly vulnerable to predation.…”

Section: Effects Of Common Capture Stressorsmentioning

confidence: 99%

“…Upon release from any gear type, fish are especially vulnerable to predators if discarded in a state of decreased responsiveness and mobility. Not surprisingly, predators have learned to associate fishing vessels and gear with opportunistic feeding on weak or incapacitated fish (Weise & Harvey, ).…”

Section: Effects Of Common Capture Stressorsmentioning

confidence: 99%

A synthesis to understand responses to capture stressors among fish discarded from commercial fisheries and options for mitigating their severity

et al. 2018

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Discarding non‐target fish from commercial fisheries is controversial and has been a persistent concern for fisheries managers globally. Discard management strategies typically begin by understanding mortality rates among discarded fish, a challenging task given the dynamic, highly context‐specific nature of fisheries. An alternative is to develop our knowledge of how stressors operate by first understanding the causes of mortality that drive this context dependence. Particularly relevant to mitigation efforts is an understanding of how fish respond to the physical factors of fishing, such as the gear itself and methods of fishing and handling the gear. We provide a synthesis of how commercial fishing methods may influence discard mortality and outline means by which capture‐induced stress and injury can be mitigated for common commercial gear types, emphasizing method variants or alternatives during capture, handling, and release that could improve survival. This synthesis identifies exhaustion and injury as the most detrimental and ubiquitous stressors experienced by discarded fish, with few options for mitigating their effects. Trawls and hanging net fisheries are identified as the most harmful gears for by‐catch, characterized by high stress regardless of method variants and limited options for mitigation. Irrespective of gear type and type of stressor, minimizing durations of capture and handling and encouragement of good handling behaviour (e.g., during landing and sorting) will reduce the magnitude of stress and injury in fish, and ultimately increase survival.

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Abundance, food habits, and annual fish consumption of California sea lion (Zalophus californianus) and its impact on salmonid fisheries in Monterey Bay, California

Cited by 10 publications

References 0 publications

Age‐ and sex‐specific survival of California sea lions (Zalophus californianus) at San Miguel Island, California

Age‐ and sex‐specific survival of California sea lions (Zalophus californianus) at San Miguel Island, California

Movement and diving behavior of male California sea lion (Zalophus californianus) during anomalous oceanographic conditions of 2005 compared to those of 2004

A synthesis to understand responses to capture stressors among fish discarded from commercial fisheries and options for mitigating their severity

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