Development and Trial of Deep-set Buoy Gear for Swordfish, Xiphias gladius, in the Southern California Bight

Sepúlveda, Chugey A.; Heberer, Craig; Aalbers, Scott A.

doi:10.7755/mfr.76.4.2

Cited by 12 publications

(26 citation statements)

References 13 publications

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“…The daytime depth distribution also revealed a deeper and more consistent depth regime when fish moved offshore, further suggesting the potential of selective targeting with deep‐set techniques. Further, when compared to other regions, the average daytime depths of PLCA swordfish are well within a range that can be readily targeted using deep‐set gear (Beverly & Robinson, ; Dewar et al., ; Sepulveda et al., ). Given the recent interest in increasing domestic production of West Coast swordfish and the heightened concern over potential protected species interactions, it is likely that any future PLCA fishery option will need to couple depth with proven gear modifications (i.e., circle hooks) to selectively target catch (Gilman et al., ; Watson, Epperly, Foster, & Shah, ).…”

Section: Discussionmentioning

confidence: 95%

Section: Discussionmentioning

confidence: 99%

“…The use of depth to selectively target swordfish and avoid non‐target species has been explored in several fisheries around the world (Gilman et al., ; Beverly et al., ), with recent research trials focused within the SCB (Sepulveda et al., ; Sepulveda & Aalbers, submitted). The SCB work suggests that daytime deep‐setting may be an option for harvesting swordfish with minimal non‐target interactions (Sepulveda et al., ). Although swordfish movements in this study were shown to be more variable than those of the SCB (Dewar et al., ; Sepulveda et al., ), the findings did reveal that the majority (57%) of the daytime records were composed of a consistent sub‐thermocline distribution.…”

Section: Discussionmentioning

confidence: 99%

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Movements and behaviors of swordfish Xiphias gladius in the United States Pacific Leatherback Conservation Area

Sepúlveda

Aalbers

Heberer

et al. 2018

Fisheries Oceanography

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This study reports on the movements of swordfish tagged within the Pacific Leatherback Conservation Area (PLCA), an expansive region (>500,000 km2) off the U.S. West Coast that has been seasonally restricted to drift‐gillnet fishing since 2001 to reduce leatherback sea turtle (Dermochelys coricea) interactions. Thirteen swordfish were outfitted with satellite‐linked archival tags scheduled for short (2–20 days, n = 11) and longer‐term (150 days, n = 2) data collection. All tags were deployed on basking swordfish using traditional harpoon‐based methods during the fall of 2012–2013, near offshore seamounts (35.6°N/122.9°W to 37.4°N/123.5°W). Depth and temperature data from 11 swordfish (~90 to 150 kg) resulted in <251 days of movement information from the PLCA region. All tagged individuals exhibited surface‐oriented nocturnal movements, spending >99% of the night above the average thermocline depth (37.5 m), with an average night depth of 8.3 ± 1.6 m. Daytime depth distribution was greater and more variable (mean 107.1 ± 21.2 m), with fish primarily displaying three behavioral patterns: (i) basking activity, 16.7% of the day, (ii) a mixed‐layer distribution between 3 m and the thermocline (26.8% of the day), and (iii) prolonged dives below the thermocline, 56.5% of the day. For seven of the tracks, daytime basking rates increased when thermocline depth was <37 m. As fish moved offshore, there was less variability in vertical movements with a reduction in both basking activity and mixed layer occupancy, as well as an increase in average daytime depth. These data are discussed with respect to the potential development of alternative fishery options for the PLCA.

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Section: Discussionmentioning

confidence: 95%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Movements and behaviors of swordfish Xiphias gladius in the United States Pacific Leatherback Conservation Area

Sepúlveda

Aalbers

Heberer

et al. 2018

Fisheries Oceanography

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“…All swordfish were tagged aboard the R / V Malolo during experimental fishing trials to test deep‐set gear configurations designed for selectively targeting west coast swordfish within the SCB (Sepulveda & Aalbers, ; Sepulveda et al, ). Gear configurations, rigging, and set protocols were standardized to align with the terms and conditions outlined in the PIER deep‐set buoy gear (DSBG) and linked‐buoy gear (LBG) exempted fishing permits (EFPs) for highly migratory species (HMS) issued through the NOAA West Coast Regional Office and approved by the Pacific Fishery Management Council (PFMC).…”

Section: Methodsmentioning

confidence: 99%

“…To better understand the horizontal movements of swordfish off the California coast, this study integrated multiple electronic tag technologies and deployed them on swordfish caught during deep‐set gear development trials (Sepulveda & Aalbers, ; Sepulveda, Heberer, & Aalbers, ). The horizontal movements and annual migration patterns are also compared to existing management unit boundaries for the region.…”

Section: Introductionmentioning

confidence: 99%

Insights into the horizontal movements, migration patterns, and stock affiliation of California swordfish

Sepúlveda

Wang

Aalbers

et al. 2020

Fisheries Oceanography

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This study reports on the horizontal movements of swordfish (Xiphias gladius L.) tagged during deep‐set fishery trials off the California coastline. Position estimates from several electronic tag types were used to better understand swordfish stock structure and regional affiliation with current boundary hypotheses used to manage swordfish in the eastern north Pacific. Swordfish were outfitted with (a) satellite‐linked mark–recapture tags (n = 66), (b) electronic data storage tags that were recaptured (n = 16), (c) fin‐mounted Argos transmitters (n = 6), and (d) satellite‐linked archival tags (n = 4). Twenty‐six percent of tagged swordfish reported close to (<225 km) their deployment location within the southern California Bight (SCB). Of the 50 swordfish that moved outside the SCB, 76% exhibited affiliation to the Eastern Pacific Ocean (EPO) management unit, 20% moved into the Western and Central North Pacific (WCNP) and 4% spent time within both the EPO and WCNP boundaries. Mean displacement between deployment and reporting locations was 1,250 ± 1,375 km, with daily rates of movement up to 55 km/day. Seasonal migrations ranged from the equator (0.8°N.132.4°W) to the Hawaiian Islands (17.0°N/154.2°W), with multiple individuals returning to the initial tagging locations the subsequent season. Seasonal site fidelity exhibited by several individuals highlights the importance of the SCB foraging grounds. While no evidence of trans‐equatorial or trans‐Pacific crossing was documented, extensive movements validate the highly migratory nature of California swordfish and support the need for future inclusion of spatial distribution data in management. Findings suggest that SCB swordfish may exhibit a higher level of EPO connectivity than previously proposed.

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Post-release survivorship and movements of bigeye thresher sharks, Alopias superciliosus, following capture on deep-set buoy gear

2019

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Development and Trial of Deep-set Buoy Gear for Swordfish, Xiphias gladius, in the Southern California Bight

Cited by 12 publications

References 13 publications

Movements and behaviors of swordfish Xiphias gladius in the United States Pacific Leatherback Conservation Area

Movements and behaviors of swordfish Xiphias gladius in the United States Pacific Leatherback Conservation Area

Insights into the horizontal movements, migration patterns, and stock affiliation of California swordfish

Post-release survivorship and movements of bigeye thresher sharks, Alopias superciliosus, following capture on deep-set buoy gear

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