scholarly journals Killer whale (Orcinus orca) depredation effects on catch rates of six groundfish species: implications for commercial longline fisheries in Alaska

2013 ◽  
Vol 70 (6) ◽  
pp. 1220-1232 ◽  
Author(s):  
Megan J. Peterson ◽  
Franz Mueter ◽  
Dana Hanselman ◽  
Chris Lunsford ◽  
Craig Matkin ◽  
...  
Keyword(s):  
Bering Sea ◽  
Killer Whale ◽  
Temporal Trends ◽  
Gulf Of Alaska ◽  
Orcinus Orca ◽  
Future Research ◽  
Fish Stock ◽  
Anoplopoma Fimbria ◽  
Catch Rates ◽  
Longline Fisheries

Abstract Peterson, M. J., Mueter, F., Hanselman, D., Lunsford, C., Matkin, C., and Fearnbach, H. 2013. Killer whale (Orcinus orca) depredation effects on catch rates of six groundfish species: implications for commercial longline fisheries in Alaska. – ICES Journal of Marine Science, 70: 1220–1232. Killer whale (Orcinus orca) depredation occurs when whales damage or remove fish caught on longline gear. This study uses National Marine Fisheries Service longline survey data from 1998–2011 to explore spatial and temporal trends in killer whale depredation and to quantify the effect of killer whale depredation on catches of six groundfish species within three management areas in Alaska: the Bering Sea, Aleutian Islands and Western Gulf of Alaska. When killer whales were present during survey gear retrieval, whales removed an estimated 54–72% of sablefish (Anoplopoma fimbria), 41–84% of arrowtooth flounder (Atheresthes stomias) and 73% (Bering Sea only) of Greenland turbot (Reinhardtius hippoglossoides). Effects on Pacific halibut (Hippoglossus stenolepis) and Pacific cod (Gadus macrocephalus) were significant in the Western Gulf only with 51% and 46% reductions, respectively. Overall catches (depredated and non-depredated sets) for all groundfish species significantly impacted by killer whale depredation were lower by 9–28% (p < 0.05). Effects on shortspine thornyhead (Sebastolobus alascanus) catches were not significant in any management area (p > 0.05). These results provide insight into the potential impacts of killer whale depredation on fish stock abundance indices and commercially important fisheries in Alaska and will inform future research on apex predator–fisheries interactions.

Grenadiers of the World Oceans: Biology, Stock Assessment, and Fisheries

2008 ◽  
Keyword(s):  
Bering Sea ◽  
Stock Assessment ◽  
Gulf Of Alaska ◽  
Pressure Change ◽  
Fishing Effort ◽  
Aleutian Islands ◽  
Anoplopoma Fimbria ◽  
Eastern Bering Sea ◽  
Mean Size ◽  
Longline Fisheries

<em>Abstract.</em>—This report summarizes biological, fishery, and survey information on giant grenadier, <em>Albatrossia pectoralis</em>, in Alaskan waters. Catch estimates of giant grenadier in Alaska for the years 1997–2005 have averaged over 16,000 metric tons (mt), and most of this catch has been taken as bycatch in longline fisheries for sablefish, <em>Anoplopoma fimbria</em>, and Greenland halibut, <em>Reinhardtius hippoglossoides</em>. The giant grenadier catch is all discarded, and none of the fish survive due to the pressure change when they are brought to the surface. Most of the catch is from the Gulf of Alaska. Data from bottom trawl and longline surveys in Alaska indicate that giant grenadier are extremely abundant in depths 300–1,000 m, and it appears this species is very important ecologically in this environment. Greatest abundance is in the western Gulf of Alaska, eastern Aleutian Islands, and in some areas of the eastern Bering Sea; abundance declines in the eastern Gulf of Alaska. Relative abundance of giant grenadier is much higher off Alaska than off the U.S. West Coast. Fish in the eastern Bering Sea and Aleutian Islands were consistently larger than those in the Gulf of Alaska. Mean size of females was larger in shallower water, and decreased with depth. Females and males appear to have different depth distributions, with females greatly predominating in depths less than 800 m. Although sex composition of giant grenadier caught in the fishery is unknown, nearly all the fishing effort is believed to be in waters less than 800 m, which indicates females are disproportionately harvested. Because of the great abundance of giant grenadier in Alaska and the relatively modest catch, overfishing of giant grenadier does not appear to be a problem at present. However, because information on the population dynamics of giant grenadier is very sparse, and because of the 100% discard mortality, the disproportionate harvest of females, and the general susceptibility of deep-sea fish to overharvest, fishery managers should monitor this species closely if catches increase in the future.

Sablefish mortality associated with whale depredation in Alaska

2017 ◽  
Vol 74 (5) ◽  
pp. 1382-1394 ◽  
Author(s):  
Megan J. Peterson ◽  
Dana Hanselman
Keyword(s):  
Killer Whale ◽  
Stock Assessment ◽  
Sperm Whale ◽  
Statistical Modelling ◽  
Gulf Of Alaska ◽  
Fish Stock ◽  
Physeter Macrocephalus ◽  
Commercial Fishery ◽  
Catch Rates ◽  
The Impact

Killer whale (Orcinus orca) and sperm whale (Physeter macrocephalus) depredation (whales removing or damaging fish caught on fishing gear) can reduce catch rates and decrease the accuracy of fish stock assessments. This study advances our understanding of the impact of whale depredation on the commercial sablefish (Anoplopoma fimbria) fishery in Alaska and evaluates the impact depredation may have on the annual federal sablefish assessment. A statistical modelling approach was used to estimate the whale effect on commercial sablefish fishery catch rates; killer whale depredation was more severe (catch rates declined by 45%–70%) than sperm whale depredation (24%–29%). Total estimated sablefish catch removals 1995–2014 ranged from 1251 t to 2407 t by killer whales in western Alaska management areas and 482 t to 1040 t by sperm whales in the Gulf of Alaska 2001–2014. Including sablefish mortality due to whale depredation on the commercial fishery in the sablefish stock assessment resulted in a 1% reduction in the recommended quota. Accounting for sablefish mortality due to whale depredation in the commercial fishery in the sablefish assessment will occur tandem with correcting for depredation on the annual National Marine Fisheries Service longline survey, the primary survey index used in the assessment.

scholarly journals Killer whale (Orcinus orca) interactions with blue-eye trevalla (Hyperoglyphe antarctica) longline fisheries

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5306 ◽  
Author(s):  
Paul Tixier ◽  
Mary-Anne Lea ◽  
Mark A. Hindell ◽  
Christophe Guinet ◽  
Nicolas Gasco ◽  
...  
Keyword(s):  
Marine Mammals ◽  
Killer Whale ◽  
Fishing Effort ◽  
Orcinus Orca ◽  
South Eastern ◽  
Operational Variables ◽  
Eastern Australia ◽  
Longline Fisheries ◽  
Fishing Area ◽  
South Eastern Australia

Over the past five decades, marine mammal interactions with fisheries have become a major human-wildlife conflict globally. The emergence of longline fishing is concomitant with the development of depredation-type interactions i.e., marine mammals feeding on fish caught on hooks. The killer whale (Orcinus orca) is one of the species most involved in depredation on longline fisheries. The issue was first reported in high latitudes but, with increasing expansion of this fishing method, other fisheries have begun to experience interactions. The present study investigated killer whale interactions with two geographically isolated blue-eye trevalla (Hyperoglyphe antarctica) fisheries operating in temperate waters off Amsterdam/St. Paul Islands (Indian Ocean) and south-eastern Australia. These two fisheries differ in the fishing technique used (vertical vs. demersal longlines), effort, catch, fleet size and fishing area size. Using 7-year (2010–16) long fishing and observation datasets, this study estimated the levels of killer whale interactions and examined the influence of spatio-temporal and operational variables on the probability of vessels to experience interactions. Killer whales interactions occurred during 58.4% and 21.2% of all fishing days, and over 94% and 47.4% of the fishing area for both fisheries, respectively. In south-eastern Australia, the probability of occurrence of killer whale interactions during fishing days varied seasonally with a decrease in spring, increased with the daily fishing effort and decreased with the distance travelled by the vessel between fishing days. In Amsterdam/St. Paul, this probability was only influenced by latitude, with an increase in the southern part of the area. Together, these findings document two previously unreported cases of high killer whale depredation, and provide insights on ways to avoid the issue. The study also emphasizes the need to further examine the local characteristics of fisheries and the ecology of local depredating killer whale populations in as important drivers of depredation.

Determining killer whale (Orcinus orca) call variability from passive acoustic monitoring in the Chukchi and Bering Sea, Alaska

2016 ◽  
Vol 140 (4) ◽  
pp. 3415-3416
Author(s):  
Brijonnay C. Madrigal ◽  
Catherine L. Berchok ◽  
Jessica L. Crance ◽  
Alison K. Stimpert
Keyword(s):  
Bering Sea ◽  
Killer Whale ◽  
Acoustic Monitoring ◽  
Orcinus Orca ◽  
Passive Acoustic Monitoring ◽  
Passive Acoustic

scholarly journals Characteristics and Variability of Storm Tracks in the North Pacific, Bering Sea, and Alaska*

2010 ◽  
Vol 23 (2) ◽  
pp. 294-311 ◽  
Author(s):  
Micheld S. Mesquita ◽  
David E. Atkinson ◽  
Kevin I. Hodges
Keyword(s):  
Bering Sea ◽  
North Pacific ◽  
Temporal Trends ◽  
Storm Track ◽  
Gulf Of Alaska ◽  
Relative Vorticity ◽  
Reanalysis Data ◽  
Storm Tracks ◽  
The North ◽  
The North Pacific

Abstract The North Pacific and Bering Sea regions represent loci of cyclogenesis and storm track activity. In this paper climatological properties of extratropical storms in the North Pacific/Bering Sea are presented based upon aggregate statistics of individual storm tracks calculated by means of a feature-tracking algorithm run using NCEP–NCAR reanalysis data from 1948/49 to 2008, provided by the NOAA/Earth System Research Laboratory and the Cooperative Institute for Research in Environmental Sciences, Climate Diagnostics Center. Storm identification is based on the 850-hPa relative vorticity field (ζ) instead of the often-used mean sea level pressure; ζ is a prognostic field, a good indicator of synoptic-scale dynamics, and is directly related to the wind speed. Emphasis extends beyond winter to provide detailed consideration of all seasons. Results show that the interseasonal variability is not as large during the spring and autumn seasons. Most of the storm variables—genesis, intensity, track density—exhibited a maxima pattern that was oriented along a zonal axis. From season to season this axis underwent a north–south shift and, in some cases, a rotation to the northeast. This was determined to be a result of zonal heating variations and midtropospheric moisture patterns. Barotropic processes have an influence in shaping the downstream end of storm tracks and, together with the blocking influence of the coastal orography of northwest North America, result in high lysis concentrations, effectively making the Gulf of Alaska the “graveyard” of Pacific storms. Summer storms tended to be longest in duration. Temporal trends tended to be weak over the study area. SST did not emerge as a major cyclogenesis control in the Gulf of Alaska.

Benthic Habitats and the Effects of Fishing

2005 ◽  
Keyword(s):  
Bering Sea ◽  
Management Practices ◽  
Gulf Of Alaska ◽  
Sea Anemones ◽  
Cancer Magister ◽  
Anoplopoma Fimbria ◽  
Distribution Maps ◽  
Resource Managers ◽  
Erimacrus Isenbeckii ◽  
The Bering Sea

<em><strong>Abstract. </strong></em>“Living substrate” has been identified as an important marine habitat and is susceptible to impacts from fishing activities. In Alaskan waters of the North Pacific and Bering Sea, little is known about the distribution of deepwater living substrate such as sponges (phylum Porifera), sea anemones (order Actiniaria), sea whips and sea pens (order Pennatulacea), ascidians (class Ascidiacea), and bryozoans (phylum Ectoprocta). Based on 26 years of survey data (mostly from catches in bottom trawls collected between 1975 and 2000), we created living substrate distribution maps. In general, the five groups of living substrate were observed in varying densities along the continental shelf and upper continental slope. Catch per unit effort (CPUE) of sponges was greatest along the Aleutian Islands, while CPUEs of ascidians and bryozoans were greatest in the Bering Sea. Large CPUEs of sea anemones, sea pens, and sea whips were observed in both the Bering Sea and the Gulf of Alaska. Broad-scale species associations between living substrate and commercially important fishes and crabs were also identified. Flatfish (Bothidae and Pleuronectidae) were most commonly associated with ascidians and bryozoans; gadids (Gadidae; also known as cods) with sea anemones, sea pens, and sea whips; rockfish (<em>Sebastes </em>spp. and shortspine thornyhead <em>Sebastolobus alascanus</em>) and Atka mackerel <em>Pleurogrammus monopterygius </em>with sponges; crabs (<em>Chionoecetes </em>spp., <em>Paralithodes </em>spp., <em>Lithodes </em>spp., Dungeness crab <em>Cancer magister</em>, and hair crab <em>Erimacrus isenbeckii</em>) with ascidians; and other commercial fish species (sablefish <em>Anoplopoma fimbria</em>, Hexagrammidae, and Rajidae) with sea pens and sea whips. These data should provide resource managers with insight into living substrate distribution and relationships among benthic community organisms and, ultimately, with future in-depth studies, may aid in determining specific areas for habitat protection and facilitate management practices that minimize fishery impacts to living substrate.

Recruitment and survival of Northeast Pacific Ocean fish stocks: temporal trends, covariation, and regime shifts

2007 ◽  
Vol 64 (6) ◽  
pp. 911-927 ◽  
Author(s):  
Franz J Mueter ◽  
Jennifer L Boldt ◽  
Bernard A Megrey ◽  
Randall M Peterman
Keyword(s):  
Bering Sea ◽  
Regime Shift ◽  
Temporal Trends ◽  
Gulf Of Alaska ◽  
Regime Shifts ◽  
Environmental Forcing ◽  
Fish Stocks ◽  
Large Marine Ecosystems ◽  
Decadal Scale ◽  
Climatic Regime

Two measures of productivity for fish stocks (recruitment and stock–recruit residuals) within two large marine ecosystems (Gulf of Alaska and eastern Bering Sea – Aleutian Islands) showed significant positive covariation within several groups of species and significant negative covariation between certain others. For example, stock–recruit residuals of gadids (Gadidae) in the Bering Sea were inversely related to those of shelf flatfishes (Pleuronectidae), suggesting that environmental forcing affects these groups in opposite ways. Salmon (Oncorhynchus spp.), Pacific herring (Clupea pallasii), and groundfish stocks each showed strong patterns of covariation within these taxonomic groups and within ecosystems, and both salmon and groundfish stocks showed positive covariation between the two ecosystems. However, we found little evidence of covariation between salmon and herring stocks or between these stocks and demersal stocks. Recruitment and stock–recruit residuals in individual stocks did not show a consistent response to known climatic regime shifts. However, combined indices of productivity across stocks showed decadal-scale variability (regime-like patterns), suggesting that both pelagic productivity (mostly salmon) and demersal productivity increased in response to the well-documented 1976–1977 climatic regime shift, whereas the 1988–1989 regime shift produced inconsistent or short-lived responses.

scholarly journals Passive acoustic monitoring of killer whales (Orcinus orca) reveals year-round distribution and residency patterns in the Gulf of Alaska

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hannah J. Myers ◽  
Daniel W. Olsen ◽  
Craig O. Matkin ◽  
Lara A. Horstmann ◽  
Brenda Konar
Keyword(s):  
Killer Whale ◽  
Marine Ecosystem ◽  
Distribution Patterns ◽  
Gulf Of Alaska ◽  
Acoustic Monitoring ◽  
Orcinus Orca ◽  
Killer Whales ◽  
Passive Acoustic Monitoring ◽  
The North ◽  
Passive Acoustic

AbstractKiller whales (Orcinus orca) are top predators throughout the world’s oceans. In the North Pacific, the species is divided into three ecotypes—resident (fish-eating), transient (mammal-eating), and offshore (largely shark-eating)—that are genetically and acoustically distinct and have unique roles in the marine ecosystem. In this study, we examined the year-round distribution of killer whales in the northern Gulf of Alaska from 2016 to 2020 using passive acoustic monitoring. We further described the daily acoustic residency patterns of three killer whale populations (southern Alaska residents, Gulf of Alaska transients, and AT1 transients) for one year of these data. Highest year-round acoustic presence occurred in Montague Strait, with strong seasonal patterns in Hinchinbrook Entrance and Resurrection Bay. Daily acoustic residency times for the southern Alaska residents paralleled seasonal distribution patterns. The majority of Gulf of Alaska transient detections occurred in Hinchinbrook Entrance in spring. The depleted AT1 transient killer whale population was most often identified in Montague Strait. Passive acoustic monitoring revealed that both resident and transient killer whales used these areas much more extensively than previously known and provided novel insights into high use locations and times for each population. These results may be driven by seasonal foraging opportunities and social factors and have management implications for this species.

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