Pelagic Research Group LLC

Honolulu, HI, United States

Pelagic Research Group LLC

Honolulu, HI, United States
Time filter
Source Type

Mourato B.L.,University of Pernambuco | Mourato B.L.,Federal University of Pernambuco | Hazin F.,University of Pernambuco | Bigelow K.,National Oceanic and Atmospheric Administration | And 3 more authors.
Fisheries Oceanography | Year: 2014

Spatial and temporal trends of sailfish catch rates in the southwestern and equatorial Atlantic Ocean in relation to environmental variables were investigated using generalized additive models and fishery-dependent data. Two generalized additive models were fit: (i) 'spatio-temporal', including only latitude, longitude, month, and year; and (ii) 'oceanographic', including sea surface temperature (SST), chlorophyll-a concentration, wind velocity, bottom depth, and depth of mixed layer and year. The spatio-temporal model explained more (average ~40%) of the variability in catch rates than the oceanographic model (average ~30%). Modeled catch rate predictions showed that sailfish tend to aggregate off the southeast coast of Brazil during the peak of the spawning season (November to February). Sailfish also seem to aggregate for feeding in two different areas, one located in the mid-west Atlantic to the south of ~15°S and another area off the north coast of Brazil. The oceanographic model revealed that wind velocity and chlorophyll-a concentration were the most important variables describing catch rate variability. The results presented herein may help to understand sailfish movements in the Atlantic Ocean and the relationship of these movements with environmental effects. © 2013 John Wiley & Sons Ltd.

Musyl M.K.,University of Hawaii at Manoa | Musyl M.K.,Pelagic Research Group LLC | Musyl M.K.,National Taiwan University | Moyes C.D.,Kingston University | And 7 more authors.
Canadian Journal of Fisheries and Aquatic Sciences | Year: 2015

 Meta-analysis (inverse-variance, random-effects model) involving 46 studies was used to estimate the effect size of postrelease mortality (Fr) in six istiophorid billfish species (black marlin (Istiompax indica), blue marlin (Makaira nigricans), longbill spearfish (Tetrapturus pfluegeri), sailfish (Istiophorus platypterus), striped marlin (Kajikia audax), and white marlin (Kajikia albida)) following release from recreational, longline, and harpoon fishing gears. The studies involved 400 reporting pop-up satellite archival tags and 64 reporting acoustic (ultrasonic) tags. Despite fish being captured, tagged, and released under widely disparate conditions, locations, and gear types, Fr was homogeneous among species. Variability in Fr was principally due to random sampling error within studies with no evident patterns. Fifteen studies (33% of tags) indicated no mortality, and the overall summary effect size for Fr was 13.5% (95% CI: 10.3%-17.6%). Since the random-effects model decomposed to a fixed-effect model when the between-studies variance T2 = 0.00, results were confirmed using exact nonparametric inferential tests and sensitivity analyses. Our results support earlier findings in the Atlantic and substantiate the majority of istiophorid billfish survive when released from recreational and longline fishing gear, clearly implying catch-and-release as a viable management option that permits fishing activity while protecting parental biomass and the fishery.

Swimmer Y.,National Oceanic and Atmospheric Administration | Empey Campora C.,Biolintec Consulting LLC | Mcnaughton L.,University of Hawaii at Manoa | Musyl M.,University of Hawaii at Manoa | And 2 more authors.
Aquatic Conservation: Marine and Freshwater Ecosystems | Year: 2014

There are few reliable estimates of post-release mortality for sea turtle species because of the many challenges and costs associated with tracking animals released at sea. In this study, the likelihood of sea turtle mortality as a result of interactions with longline fishing gear was estimated based on satellite telemetry data, such as the number of days an animal was successfully tracked, or days at liberty (DAL) and dive depth data, as well as anatomical hooking locations. Pop-up satellite archival tags were deployed on 29 loggerhead sea turtles (Caretta caretta) caught by the North Pacific US-based pelagic longline fishery operating from California and Hawaii between 2002 and 2006. Loggerhead turtles were catagorized by observers as shallow-hooked (55%) if the animal was entangled in the line or the hook was in the flipper, jaw or mouth and could be removed, or deep-hooked (45%) if the hook was ingested and could not be removed. The vertical movements of turtles were used to infer potential mortalities. Of the 25 tags that reported data, the DAL ranged from 3 to 243 days (mean=68 days). The DAL was shorter (by nearly 50%) for shallow-hooked (mean=48 days, range: 3 to 127) compared to deep-hooked turtles (mean=94 days, range: 5 to 243), but these changes were not statistically significant (P=0.0658). Although aspects of these analyses may be considered speculative, these data provide empirical evidence to indicate that deep-hooking is not linked to shorter DAL. DAL, anatomical hooking location, and gear removal were evaluated with inferences about the extent of injuries and rates of infection to estimate an overall post-release mortality rate of 28% (95% bootstrap CI: 16-52%). This range of estimates is consistent with those used to shape some US fisheries management plans, suggesting that conservation goals are being achieved at the expected level and ideally striking a balance between the interests of industry and those of protected species. Copyright © 2013 John Wiley & Sons, Ltd. © 2013 John Wiley & Sons, Ltd.

Chiang W.-C.,Taiwanese Fisheries Research Institute | Musyl M.K.,Pelagic Research Group LLC | Musyl M.K.,National Taiwan University | Sun C.-L.,National Taiwan University | And 7 more authors.
Fisheries Research | Year: 2015

Black marlin (Istiompax indica) is a highly migratory apex predator distributed widely throughout the Pacific and Indian Oceans, with seasonal densities occurring in the East and South China Seas and near Taiwan. The peak seasonal presence of black marlin in eastern Taiwan (September to November) has led to the development of a commercially important harpoon fishery that specifically targets this aggregation. The harpoon fishery provides relatively easy access to black marlin for tagging research to monitor their movement patterns with pop-up satellite archival tags (PSATs). Nine black marlin were tagged from February 2011 to March 2012 with PSATs that acquired depth, temperature and ambient light-level data. PSATs remained affixed for a median 95 days (average 132 days±38 SE, range: 10-360 days) which are the highest documented PSAT retention statistics for any istiophorid billfish. No post-release mortalities occurred in these data and the harpoon method of PSAT application, as well as an improved anchor, may promote longer retention times by tagging fish that are not subjected to stress or injury associated with prolonged fishing bouts or handling. Linear displacements ranged from 567 to 1226km from deployment to pop-up locations with speeds of 3.1-122.6kmday-1 (average: 6.4kmday-1, 0.3kmh-1). Most probable tracks calculated by the state-space Kalman filter, augmented with sea surface temperature (SST), suggested that black marlin undergo dichotomous seasonal movement patterns: fishes tagged in spring and summer moved in a northerly direction to the East China Sea and those tagged in winter moved in a southerly direction to the South China Sea. Estimated track models during March-April for tagged fish in southwestern Taiwan coincided with known spawning activity in this vicinity though the tracks and vertical data were not sufficiently detailed to discriminate this putative behaviour. Diving depths ranged from the surface to ~258m and ambient water temperatures occupied ranged from 30.3°C to 14.5°C. The distribution of time spent at depth and temperature was significantly different between daytime and nighttime diving activity. Tagged black marlin spent the majority of daytime in the surface mixed-layer to ~50m and exhibited occasional basking behaviour; and at nighttime, they were confined almost exclusively to the surface to ~20m. Depth distribution appeared to be limited by an 8°C change in water temperature relative to the warmest water (δSST). In the context of regional fisheries management and stock assessments, our study reports the first tagging data of black marlin in Southeast Asia and it will be especially important to compare diving behaviour patterns with other specimens tagged using other fishing methods to discern differences. Like many previous electronic tagging studies on istiophorid billfish in the Pacific, the data suggest that the majority of habitat for black marlin in Taiwan may be adequately described by two dimensions (this species spends most of their time in the surface mixed-layer). © 2014 Elsevier B.V.

Chiang W.-C.,Taiwanese Fisheries Research Institute | Kawabe R.,Nagasaki University | Musyl M.K.,Pelagic Research Group LLC | Sun C.-L.,National Taiwan University | And 7 more authors.
Journal of Marine Science and Technology (Taiwan) | Year: 2013

A sailfish (Istiophorus platypterus) was tagged with a pop-up satellite archival tag off the eastern coast of Taiwan and moved in a northerly direction to the East China Sea, where the tag popped-up after 160 days. The total linear displacement was 550 km from deployment to pop-up location and all movements were confined to the East China Sea. After the primarily southward movement during first two months at-liberty, the sailfish changed course after September and began to swim in a northerly direction paralleling the Kuroshio Current. During these horizontal movements, the tagged animal exhibited diel oscillations in its vertical diving behavior. On 22 days of the entire 160 days-at-liberty, the sailfish dove to depths deeper than 100 m. The sailfish spent >85% of its time in the upper uniformly mixed layer above ∼50 m, but made more extensive vertical movements during the daytime ( x̄ = 32.2 m ± 34.5 SD) than nighttime ( x̄ = 9.5 m ± 16.7 SD). Depths and ambient water temperatures visited ranged from 0 to 153 m and 29.7°C to 17.8°C, respectively. The depth distribution appeared to be limited by ∼6°C to 8°C changes in water temperature (Delta T) relative to sea surface temperature.

Mourato B.L.,Federal University of São Paulo | Carvalho F.,University of Florida | Musy M.,Pelagic Research Group LLC | Amorim A.,Institute Pesca SAA SP | And 3 more authors.
Neotropical Ichthyology | Year: 2014

Pop-up satellite archival tags (PSATs) were deployed on four sailfish, Istiophorus platypterus, in the coastal waters of Rio de Janeiro State in southeast Brazil during January and February of 2009 (sailfish I and II) and between November 2010 and January 2011 (sailfish III and IV). The total number of days monitored (i.e., time that the tags remained attached) were 12 (sailfish I), 51 (sailfish II), 16 (sailfish III) and 43 days (sailfish IV). The results indicate a clear pattern of vertical habitat utilization with the majority of the time spent concentrated near the uniform sea surface layer occupying a relatively narrow temperature range. Despite the clear preference for epipelagic surface waters, sailfish regularly undertook vertical excursions into deeper waters (>50 m) within three to six hour intervals. "Most Probable Tracks" (estimated from raw geolocations using the state-space Kalman filter model) and linear displacements suggested that tagged sailfish did not move significant distances from the tagging site. In brief, our report provides information regarding the biology of sailfish in the southwestern Atlantic and how vertical distributions during the day and night are influenced by water temperature and how this information can improve sailfish stock assessments in southwestern Atlantic Ocean. © 2014 Sociedade Brasileira de Ictiologia.

Loading Pelagic Research Group LLC collaborators
Loading Pelagic Research Group LLC collaborators