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Robert W Hannah - One of the best experts on this subject based on the ideXlab platform.
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use of a novel cage system to measure postrecompression survival of northeast pacific Rockfish
Marine and Coastal Fisheries: Dynamics Management and Ecosystem Science, 2012Co-Authors: Robert W Hannah, Polly S Rankin, Matthew T O BlumeAbstract:Abstract We used a caging system designed to minimize the adverse effects of caging fish in marine waters to evaluate the discard mortality of seven species of Rockfish Sebastes with barotrauma. Altogether, 288 Rockfish were captured, scored for barotrauma, evaluated behaviorally at the surface, and caged individually on the seafloor for 48 h to determine survival. With the exception of three blue Rockfish S. mystinus, the condition of surviving fish after cage confinement from 41 to 71 h was excellent. At capture depths up to 54 m, survival was 100% for yelloweye Rockfish S. ruberrimus (n = 25) and copper Rockfish S. caurinus (n = 10) and 78% for blue Rockfish (n = 36). At capture depths up to 64 m, survival was 100% for canary Rockfish S. pinniger (n = 41) and quillback Rockfish S. maliger (n = 28) and 90% for black Rockfish S. melanops (n = 144). Black Rockfish survival was negatively associated with capture depth (m) and the surface–bottom temperature differential (°C). Blue Rockfish survival was nega...
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Site Fidelity and Movement of Eight Species of Pacific Rockfish at a High-Relief Rocky Reef on the Oregon Coast
North American Journal of Fisheries Management, 2011Co-Authors: Robert W Hannah, Polly S RankinAbstract:Abstract We used acoustic telemetry techniques to study the movements of eight species of Pacific Rockfish (genus Sebastes) inhabiting Siletz Reef, a high-relief rocky reef complex on the Oregon coast. Our primary interest was evaluating potential residence times for Rockfish species in small, no-take marine protected areas (MPAs) like those recently designated for Oregon waters (337–1,502 ha). We tagged 6 black Rockfish S. melanops, 31 canary Rockfish S. pinniger, 9 yelloweye Rockfish S. ruberrimus, 5 quillback Rockfish S. maliger, and 2 copper Rockfish S. caurinus, along with single specimens of china Rockfish S. nebulosus, vermilion Rockfish S. miniatus, and tiger Rockfish S. nigrocinctus, and monitored their movements with a large (about 5,200-ha) receiver grid for over a year. Canary Rockfish showed low site fidelity and wide-ranging movements that exceeded the scale of our detection grid and a wide range of vertical movements (up to 27 m). Quillback, vermilion, tiger, china, and some yelloweye rockf...
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Physical model of the development of external signs of barotrauma in Pacific Rockfish
Aquatic Biology, 2008Co-Authors: Robert W Hannah, Polly S Rankin, Alexandra N. Penny, Steven J. ParkerAbstract:Four species of Sebastes (Pacific Rockfish) showed evidence of a wide array of internal injuries from capture-induced barotrauma, including liver and swimbladder damage, organ displace- ment related to esophageal eversion, and hemorrhage in the pericardium and abdominal cavity. However, clear evidence of swimbladder rupture was not observed in all fish with external signs of barotrauma. Injection of air through the body wall into the swimbladders of Rockfish carcasses gen- erated all of the common external signs of barotrauma documented in wild-captured fish, suggesting that the physical effects of swimbladder gas expansion can create these gross external signs without embolism from dissolved blood gases. Dissections of injected black Rockfish S. melanops carcasses showed that, typically, injected air escaped the swimbladder without obvious rupture, moving in an anterio-dorsal direction, generating bulges and air bubbles that were externally visible through the branchiostegal membrane. Injected air also collected dorsally to the esophagus, posterior to the pha- ryngeal teeth, causing the esophagus to roll outwards into the buccal cavity (esophageal eversion). Injected air also frequently traveled further forward, collecting medially to the eyeball, leading to exophthalmia, and then moved distally along the fascia, invading the corneal stroma from the edges, resulting in corneal emphysemas. Air injected into the swimbladders of quillback Rockfish S. maliger carcasses generated similar eye effects, but also escaped through ruptures in the branchiostegal membrane and did not generate esophageal eversion, which is also infrequent in wild-caught speci- mens. These results demonstrate that the major external signs of barotrauma in Pacific Rockfish can develop as result of escaping swimbladder gases following an internal 'path of least resistance'.
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escaping the surface the effect of capture depth on submergence success of surface released pacific Rockfish
North American Journal of Fisheries Management, 2008Co-Authors: Robert W Hannah, Steven J. Parker, Keith M MattesonAbstract:Abstract We evaluated the effect of capture depth and fish size on the ability of several Pacific Rockfishes Sebastes spp. to resubmerge after hook-and-line capture and surface release. We observed fish as they were released into a bottomless floating enclosure, and we recorded submergence success within a 5-min time limit. Submergence success was greater than 80% for all Rockfish captured in depths less than 30 m. Yellowtail Rockfish S. flavidus (N = 51) were 100% successful at submerging in less than 49 s at all depths sampled (10–51 m). At capture depths of 40–51 m, submergence success was 89% for quillback Rockfish S. maliger (N = 9), 65% for black Rockfish S. melanops (N = 46), and 30% for canary Rockfish S. pinniger (N = 40). At depths of 30–51 m, submergence success was 32% for blue Rockfish S. mystinus (N = 31). The external signs of barotrauma (e.g., exopthalmia, eversion of the esophagus) increased with depth of capture and were least prevalent in yellowtail Rockfish and quillback Rockfish. The ...
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behavior of nine species of pacific Rockfish after hook and line capture recompression and release
Transactions of The American Fisheries Society, 2007Co-Authors: Robert W Hannah, Keith M MattesonAbstract:Abstract We evaluated the effect of barotrauma on the behavior of nine species of Pacific Rockfish Sebastes spp. after hook-and-line capture and release using a video-equipped underwater release cage. Sampling was conducted across a range of bottom depths (12–194 m), mostly where barotrauma resulting from an expanded swim bladder and gaseous release of dissolved blood gases would be expected. Behavioral impairment from barotrauma was depth related but highly species specific. Increased depth of capture was associated with lower behavioral scores for black Rockfish S. melanops, blue Rockfish S. mystinus, and yelloweye Rockfish S. ruberrimus, but not for canary Rockfish S. pinniger. Behaviorally impaired fish showed a decreased ability to maintain vertical orientation and were slower in exiting the release cage. Species differed in the degree of behavioral impairment resulting from barotrauma and in how rapidly behavioral impairment increased with depth of capture. When captured at depths between 40 and 99 ...
Darren R Grocke - One of the best experts on this subject based on the ideXlab platform.
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regional ecological variability and impact of the maritime fur trade on nearshore ecosystems in southern haida gwaii british columbia canada evidence from stable isotope analysis of Rockfish sebastes spp bone collagen
Archaeological and Anthropological Sciences, 2013Co-Authors: Paul Szpak, Trevor J Orchard, Anne K Salomon, Darren R GrockeAbstract:The maritime fur trade (1785–1840s) led to the local extinction of sea otters (Enhydra lutris) in many parts of the northeast Pacific. On the basis of studies of extant sea otter populations, it has been established that they have a disproportionate effect on nearshore ecosystems by limiting sea urchin abundance and facilitating the establishment of nearshore kelp forests; in the absence of sea otters, a local reduction in kelp-derived carbon is therefore expected. We measured the isotopic composition (δ13C and δ15N) of Rockfish (Sebastes spp.) bone collagen from late Holocene archaeological sites in southern Haida Gwaii, BC, Canada, using δ13C as a proxy for kelp-derived carbon in the diet and δ15N as a proxy for trophic position. We observed significant spatial variability in Rockfish kelp-derived carbon (δ13C), but not trophic level (δ15N). Kelp-derived carbon varied largely as a function of site characteristics (wave exposure), suggesting that local oceanographic conditions are important factors with respect to consumer tissue isotopic compositions. Kelp-derived carbon decreased in post-European contact Rockfish relative to pre-European contact Rockfish, likely as a result of the reduction of kelp forests associated with the local extirpation of sea otters. Although we detected a reduction in kelp-derived carbon in Rockfish diets, we found no shift in trophic level at sites occupied following the maritime fur trade. This implies a shift in local ecosystems, and particularly in carbon sources, following the maritime fur trade, likely due to a trophic cascade resulting from the local extirpation of sea otters. Stability in Rockfish trophic levels, however, implies that Rockfish continued to feed at similar trophic levels, consuming prey with similar nitrogen isotopic compositions.
Keith M Matteson - One of the best experts on this subject based on the ideXlab platform.
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escaping the surface the effect of capture depth on submergence success of surface released pacific Rockfish
North American Journal of Fisheries Management, 2008Co-Authors: Robert W Hannah, Steven J. Parker, Keith M MattesonAbstract:Abstract We evaluated the effect of capture depth and fish size on the ability of several Pacific Rockfishes Sebastes spp. to resubmerge after hook-and-line capture and surface release. We observed fish as they were released into a bottomless floating enclosure, and we recorded submergence success within a 5-min time limit. Submergence success was greater than 80% for all Rockfish captured in depths less than 30 m. Yellowtail Rockfish S. flavidus (N = 51) were 100% successful at submerging in less than 49 s at all depths sampled (10–51 m). At capture depths of 40–51 m, submergence success was 89% for quillback Rockfish S. maliger (N = 9), 65% for black Rockfish S. melanops (N = 46), and 30% for canary Rockfish S. pinniger (N = 40). At depths of 30–51 m, submergence success was 32% for blue Rockfish S. mystinus (N = 31). The external signs of barotrauma (e.g., exopthalmia, eversion of the esophagus) increased with depth of capture and were least prevalent in yellowtail Rockfish and quillback Rockfish. The ...
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behavior of nine species of pacific Rockfish after hook and line capture recompression and release
Transactions of The American Fisheries Society, 2007Co-Authors: Robert W Hannah, Keith M MattesonAbstract:Abstract We evaluated the effect of barotrauma on the behavior of nine species of Pacific Rockfish Sebastes spp. after hook-and-line capture and release using a video-equipped underwater release cage. Sampling was conducted across a range of bottom depths (12–194 m), mostly where barotrauma resulting from an expanded swim bladder and gaseous release of dissolved blood gases would be expected. Behavioral impairment from barotrauma was depth related but highly species specific. Increased depth of capture was associated with lower behavioral scores for black Rockfish S. melanops, blue Rockfish S. mystinus, and yelloweye Rockfish S. ruberrimus, but not for canary Rockfish S. pinniger. Behaviorally impaired fish showed a decreased ability to maintain vertical orientation and were slower in exiting the release cage. Species differed in the degree of behavioral impairment resulting from barotrauma and in how rapidly behavioral impairment increased with depth of capture. When captured at depths between 40 and 99 ...
Samuel J. Hochhalter - One of the best experts on this subject based on the ideXlab platform.
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Modeling submergence success of discarded yelloweye Rockfish (Sebastes ruberrimus) and quillback Rockfish (Sebastes maliger): Towards improved estimation of total fishery removals
Fisheries Research, 2012Co-Authors: Samuel J. HochhalterAbstract:Abstract Identification of variables that can be used to predict discard mortality is an important step towards improving estimates of total fishery removals. I explored the utility of capture depth, six external signs of barotrauma, two behavioral responses, and an impairment index that summed the physical and behavioral impairment associated with rapid decompression at predicting the submergence success of hook-and-line captured yelloweye ( n = 95) and quillback ( n = 65) Rockfish that were released at the water's surface. Random forests classification models were used to identify the relative importance of predictor variables ( n = 11) for each species and to explore the ability of these variables to accurately predict individual submergence success. Capture depth was identified as the most important variable in predicting yelloweye Rockfish submergence but provided little improvement to the quillback Rockfish model. The impairment index and the barotrauma sign associated with maximal gas retention were identified as important predictor variables for both yelloweye and quillback Rockfish. These findings suggest that the impairment index, unlike capture depth, was able to account for individual variability in submergence success or failure of quillback Rockfish.
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the effectiveness of deepwater release at improving the survival of discarded yelloweye Rockfish
North American Journal of Fisheries Management, 2011Co-Authors: Samuel J. Hochhalter, Daniel J ReedAbstract:Abstract The effectiveness of deepwater release at improving the 17-d survival of discarded yelloweye Rockfish Sebastes ruberrimus was determined by comparing an estimate of survival for individuals released at depth with an estimate of submergence probability for individuals released at the water's surface. A mark–recapture study was used to generate a maximum likelihood estimate of the 17-d survival probability of yelloweye Rockfish (n = 182) caught by hook and line (depth = 18–72 m) and subsequently released at depth. The average Cormack–Jolly–Seber survival probability for yelloweye Rockfish released at depth was remarkably high (0.988; 95% confidence interval = 0.478–0.999) and positively correlated with individual total length. Survival probability was not significantly influenced by the range of capture depths explored in this study or by exposure to barotrauma and other capture stressors. The submergence success of yelloweye Rockfish released at the water's surface was 0.221 (95% confidence interv...
Paul Szpak - One of the best experts on this subject based on the ideXlab platform.
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regional ecological variability and impact of the maritime fur trade on nearshore ecosystems in southern haida gwaii british columbia canada evidence from stable isotope analysis of Rockfish sebastes spp bone collagen
Archaeological and Anthropological Sciences, 2013Co-Authors: Paul Szpak, Trevor J Orchard, Anne K Salomon, Darren R GrockeAbstract:The maritime fur trade (1785–1840s) led to the local extinction of sea otters (Enhydra lutris) in many parts of the northeast Pacific. On the basis of studies of extant sea otter populations, it has been established that they have a disproportionate effect on nearshore ecosystems by limiting sea urchin abundance and facilitating the establishment of nearshore kelp forests; in the absence of sea otters, a local reduction in kelp-derived carbon is therefore expected. We measured the isotopic composition (δ13C and δ15N) of Rockfish (Sebastes spp.) bone collagen from late Holocene archaeological sites in southern Haida Gwaii, BC, Canada, using δ13C as a proxy for kelp-derived carbon in the diet and δ15N as a proxy for trophic position. We observed significant spatial variability in Rockfish kelp-derived carbon (δ13C), but not trophic level (δ15N). Kelp-derived carbon varied largely as a function of site characteristics (wave exposure), suggesting that local oceanographic conditions are important factors with respect to consumer tissue isotopic compositions. Kelp-derived carbon decreased in post-European contact Rockfish relative to pre-European contact Rockfish, likely as a result of the reduction of kelp forests associated with the local extirpation of sea otters. Although we detected a reduction in kelp-derived carbon in Rockfish diets, we found no shift in trophic level at sites occupied following the maritime fur trade. This implies a shift in local ecosystems, and particularly in carbon sources, following the maritime fur trade, likely due to a trophic cascade resulting from the local extirpation of sea otters. Stability in Rockfish trophic levels, however, implies that Rockfish continued to feed at similar trophic levels, consuming prey with similar nitrogen isotopic compositions.
