Spiny Dogfish Squalus Acanthias Research Articles

Sexual Segregation of Spiny Dogfish in Fishery‐Dependent Surveys in Cape Cod, Massachusetts: Potential Management Benefits

AbstractCommercial gill‐net and longline surveys were conducted in the Cape Cod, Massachusetts, area to assess whether the proportion of male Spiny Dogfish Squalus acanthias in the catch changes throughout a normal fishing day (an event frequently observed by local commercial longliners) and to identify the associated potential benefits for fishery management in the study area. Sex ratio changes were examined with respect to location (north and south of 42°N), environment (depth, surface and bottom temperatures, and salinity) and fishing (type of gear and time of activity). Spiny Dogfish showed differences in sex ratios (the proportion of males in the catch [PM]) that were related to location and type of fishing gear as well as to depth and time. Higher numbers of fish were caught with longlines, and higher numbers of males were caught in the southern area in inshore shallower waters early in the day. In the northern area, the sex distribution found within sets indicated a higher presence of females and a lower presence of males in shallower inshore waters. Changes in environmental parameters (depth and bottom temperature) were correlated with PM only in the south. A consistent seasonal (summer and early fall) diurnal shift in the sex ratio was found within 10 mi (16.1 km) of the east coast of the Cape Cod peninsula. This shift suggests that the implementation of a seasonal, male‐only directed longline fishery be considered for this location. Such a fishery would enhance the sustainability of the U.S. Atlantic Spiny Dogfish stock by reducing fishing pressure on adult females. The sex ratios observed suggest that sexual segregation in Spiny Dogfish in the Cape Cod area corresponds to female avoidance of males coupled with specific mating and/or feeding behavior by males.Received March 19, 2013; accepted November 20, 2013

Feeding Habits, Daily Ration, and Potential Predatory Impact of Mature Female Spiny Dogfish in North Carolina Coastal Waters

AbstractThough the feeding habits of Spiny Dogfish Squalus acanthias in the northwestern Atlantic Ocean have received much attention due to their potential interactions with fisheries, currently no estimate of daily ration specific to the northwestern Atlantic population has been determined. To assess the diet of these sharks in the southern extent of their range, stomach contents were collected from 255 Spiny Dogfish captured by bottom trawl in nearshore North Carolina waters; 244 were mature females. Prey items were identified and percent index of relative importance was calculated for each prey taxon and category. To determine daily ration, 15 mature female Spiny Dogfish were captured by hook and line in North Carolina waters and kept in captivity for 2 weeks of feeding trials. Dogfish were fed preweighed frozen Atlantic Menhaden Brevoortia tryannus and allowed to digest their prey for predetermined periods, after which remaining food was removed using stomach‐tube gastric lavage. Gastric evacuation rates determined by feeding trials were combined with data collected from sampling stomach contents to determine the daily ration and the amount of important prey taxa consumed during the Spiny Dogfish overwintering period. Teleost fishes were the dominant prey category, and Atlantic Menhaden and Bay Anchovy Anchoa mitchilli were the most important prey taxa. Daily ration estimates ranged from 0.26% to 0.56% of the shark's body weight per day. Spiny Dogfish potentially consumed an equivalent of 1.55–3.33% of the Atlantic Menhaden stock while overwintering in North Carolina waters.Received July 23, 2013; accepted March 5, 2014

Comparative Studies of Hepatic and Blood Biomarkers in Three Species of Black Sea Elasmobranchs

The investigations of elasmobranchs are very important for the understanding of evolutionary process and mechanisms of fish adaptation. Fishing pressure and global climate changes are affecting elasmobranch population size and structure. Baseline data of these taxa from different locations are useful for the evaluation of their health and for development of the methods of their preservation. In this study Aminotransferases (ALT and AST) activity, oligopeptides, albumin and hemoglobin concentrations were determined in the liver, red blood cells and blood serum of three Black Seaelasmobranch species: Atlantic spiny dogfish Squalus acanthias, buckler skate Raja clavata and stringray Dasyatis pastinaca. Interspecies differences of enzymatic activities depending on fish biology and ecology were shown. Hepatic aminotransferases level and serum oligopeptides concentration were greater in benthic/pelagic active shark, than in benthic sluggish rays. Oligopeptides concentration in red blood cells was the similar in tested elasmobranchs, while serum enzymatic activity and hepatic oligopetides level were higher in R. clavata than in D. pastinaca and S. acanthias inhabiting deeper waters. The results demonstrate that the complex of biochemical characteristics of elasmobranchs together with their ecological specificity can be used to indicate the main strategy of biochemical adaptation of fish evolutionary process.

A step forward in development of fish protein hydrolysate-based diets for larvae of Japanese eel Anguilla japonica

Eggs of spiny dogfish Squalus acanthias are an indispensable and effective component of the compound diets currently used for larvae of the Japanese eel Anguilla japonica. However, this fish species, a natural resource, is becoming more scarce, suggesting that suitable diets should be developed using more sustainable components. In the search for appropriate diets without shark eggs, we have designed test diets in which shark eggs were replaced with general feed materials, such as fish protein hydrolysate (FPH), with the notable improvement that the FPH had been pre-digested with integral enzymes from frozen krill. Feeding trials were conducted to assess the effects of the test diets on survival and growth of Japanese eel larvae at early developmental stages. Larvae fed on the test diets were found to be able to survive up to 65 days after hatching, the maximum total length and body depth were 14.1 and 1.5 mm, respectively. Although larvae fed on the test diets still exhibited a low survival rate and poor growth, the FPH-based diets had a nutritional value that promoted substantial larval growth based on the significant difference between the initial and final body sizes. Our results suggest that the development of FPH-based diets not based on shark eggs but rather on general feed ingredients is promising but that there is much room for improvement.

Maturation, fecundity and reproductive cycle of spiny dogfish, Squalus acanthias, in the Adriatic Sea

We provide the first detailed information on the reproductive traits of the endangered spiny dogfish (Squalus acanthias) in the Adriatic Sea, based upon 224 specimens (132 females and 92 males) collected onboard of commercial bottom trawls between 2005 and 2007. The morphometry of gonads, gonadosomatic index (GSI) and histological examination of gonads were used to analyse maturation and gonadal development of the species. The length at 50% maturity was attained at 504 mm for males and 725 mm for females. Ovarian fecundity ranged from 4 to 18 follicles (mean±SD: 10.8±4.5) and uterine fecundity ranged from 6 to 18 embryos (mean±SD: 10.1±3.9). Total length of embryos with absorbed yolk sacs ranged between 200 and 215 mm. The GSI and the high proportion of mature spermatocysts in the testes suggests that a majority of mating activity occurs in June, November and December, while the seasonal distribution of the largest ova and full-term embryos indicate that ovulation and parturition occur during the summer. In comparison with other study areas, spiny dogfish in the Adriatic Sea attained sexual maturity at smaller sizes and obtained higher fecundity values than fish from other regions.

Development of a Nonlethal and Minimally Invasive Protocol to Study Elasmobranch Reproduction

AbstractAn understanding of basic reproductive biology is essential for successful species‐specific management of elasmobranch fishes (sharks, skates, and rays). Such information is often gained through gross dissection or other lethal techniques, which are not appropriate for threatened and endangered species. Previous work on other vertebrates suggested that sex steroid hormones can be extracted from muscle tissues to identify reproductive status. Collecting for muscle biopsy is quick and minimally invasive and can be done without removing an animal from the water. Thus, the objective of the current study was to determine the efficacy of using muscle steroid hormones to assess the reproductive biology of elasmobranch fishes. The results suggest that concentrations of muscle progesterone, testosterone, and estradiol can be successfully quantified to study reproduction by radioimmunoassay. Additionally, there were significant correlations between the plasma and muscle estradiol concentrations in Spiny Dogfish Squalus acanthias and the progesterone, testosterone, and estradiol concentrations in Atlantic Sharpnose Sharks Rhizoprionodon terraenovae. The present investigation thus demonstrates that skeletal muscle is a nonlethally harvestable tissue that is well suited for studying the reproductive biology of elasmobranchs.Received October 12, 2012; accepted March 12, 2013

Reproductive Biology of Spiny Dogfish Squalus acanthias, in the North Aegean Sea

Kuzey Ege Denizi, Saros Korfezi’nde, Subat 2005-Eylul 2008 tarihleri arasinda, dip trolu ile toplam 620 adet Squalus acanthias orneklenmistir. Orneklerin tumunde cinsiyet oranlari 1.26:1’dir. Disilerin toplam boylari 17,1’den 117,5 cm’e, erkeklerin ise 20,8’den 121,6 cm’e degisim gostermistir. Disiler pozitif allometrik buyume (b>3), erkekler negatif allometrik buyume gostermistir (b<3). Erkekler ve disiler arasinda, toplam boy-toplam agirlik ve karaciger agirligi-toplam boy iliskileri istatistiksel olarak onemli derecede bulunmustur. Cinsi olgunluga erisen en kucuk disi 54,5 cm toplam boya sahipken, cinsi olgunluga erisen en kucuk erkek 52 cm toplam boydadir. Bireylerin %50’de ulastigi ilk cinsi olgunluk boyu disilerde 56,4 cm iken, erkeklerde 52,8 cm’dir. Oositlerin agirliklari 0,01 ile 36,24 g arasinda degisim gosterirken, caplari 0,5 mm ve 46 mm arasinda oldugu belirlenmistir. Hepatosomatik indeks (HSI) ve gonadosomatik indeks (GSI) degerleri, hem disi hem erkeklerin boylari ile onemli derecede artis gostermistir. HSI ve GSI degerleri sirasiyla, erkeklerde 1,93-14,09% ve 0,0134,35% arasinda degisirken, disilerde 1,63-17,17% ve 0,01-96,50% arasinda degisim gostermistir. Karacigerin ureme donemine etkisinden dolayi, HSI degerleri hem yetismekte olan hem de yetiskin bireylerde en yuksek degerine ulasmistir.

Hen egg yolk and skinned krill as possible foods for rearing leptocephalus larvae ofAnguilla japonicaTemminck &amp; Schlegel

Usual diets for rearing leptocephalus larvae of Japanese eel Anguilla japonica include eggs of the endangered spiny dogfish Squalus acanthias (SE). We investigated the effects of alternative food materials, hen egg yolk (HEY) and exoskeleton-free (skinned) Antarctic krill (SAK), on the growth and survival of eel larvae. We found that feed comprising whole krill including exoskeleton (WAK) containing higher levels of fluoride (37.89 mg kg−1) was acutely toxic to eel larvae exposed to this alone. In contrast, extract from SAK containing lower concentrations of fluoride (4.25 mg kg−1) showed no apparent adverse effects. Growth of larvae fed a mixture of SE and SAK in a feed trial of 58 days [mean body weight (BW), 6.0 mg] was about twofold higher than that of larvae fed a mixture of SE and WAK (3.2 mg) (P < 0.01). A mixture of HEY and SAK also had some dietary benefits for eel larvae, enabling them to survive for up to 58 days and to grow significantly (mean BW, 2.4 mg), compared with their initial weight (mean BW, 0.2 mg) (P < 0.001). Although additional nutritional improvements are needed, the present results suggest that combination diet HEY and SAK may be a good alternative to SE as an effective diet for eel larvae.

Cell and molecular biology of the spiny dogfish Squalus acanthias and little skate Leucoraja erinacea: insights from in vitro cultured cells

Two of the most commonly used elasmobranch experimental model species are the spiny dogfish Squalus acanthias and the little skate Leucoraja erinacea. Comparative biology and genomics with these species have provided useful information in physiology, pharmacology, toxicology, immunology, evolutionary developmental biology and genetics. A wealth of information has been obtained using in vitro approaches to study isolated cells and tissues from these organisms under circumstances in which the extracellular environment can be controlled. In addition to classical work with primary cell cultures, continuously proliferating cell lines have been derived recently, representing the first cell lines from cartilaginous fishes. These lines have proved to be valuable tools with which to explore functional genomic and biological questions and to test hypotheses at the molecular level. In genomic experiments, complementary (c)DNA libraries have been constructed, and c. 8000 unique transcripts identified, with over 3000 representing previously unknown gene sequences. A sub-set of messenger (m)RNAs has been detected for which the 3' untranslated regions show elements that are remarkably well conserved evolutionarily, representing novel, potentially regulatory gene sequences. The cell culture systems provide physiologically valid tools to study functional roles of these sequences and other aspects of elasmobranch molecular cell biology and physiology. Information derived from the use of in vitro cell cultures is valuable in revealing gene diversity and information for genomic sequence assembly, as well as for identification of new genes and molecular markers, construction of gene-array probes and acquisition of full-length cDNA sequences.

Diets and Trophic Linkages of Epipelagic Fish Predators in Coastal Southeast Alaska during a Period of Warm and Cold Climate Years, 1997–2011

AbstractThis study identifies important trophic links for epipelagic marine fish predators in Southeast Alaska to improve understanding of marine ecosystem dynamics in response to climate change. Fish predators can be viewed as autonomous samplers whose diets should integrate the available prey taxa commensurate with environmental conditions. We examined fish predators from annual (1997–2011) surveys conducted in May to September by the Southeast Coastal Monitoring (SECM) project of Auke Bay Laboratories in the marine waters of Southeast Alaska. This project has emphasized long‐term monitoring of strait and coastal marine habitats used by juvenile Pacific salmon Oncorhynchus spp. and associated epipelagic fishes to understand how environmental variation affects the sustainability of salmon resources. From 1,295 surface trawl hauls, trophic links were identified for 2,473 fish representing 19 predator species, principally adult and immature salmon, immature walleye pollock Theragra chalcogramma, and spiny dogfish Squalus acanthias. The most common fish prey consumed were fish larvae, juvenile salmon, Pacific herring Clupea pallasii, capelin Mallotus villosus, walleye pollock, lanternfishes (Myctophidae), and Pacific sand lance Ammodytes hexapterus, whereas the most common invertebrate prey consumed were euphausiids, decapod larvae, pteropods, and amphipods. This study describes the degree of piscivory, incidence of juvenile salmon prey, and frequency and weight composition of prey in the diets of epipelagic fish predators, but it did not clearly detect an effect of warm‐versus‐cold climate years on the diets of key planktivorous or piscivorous predators over the 15‐year time series. Identifying the persistence of trophic links in epipelagic waters over time is important because climate‐related changes in the upper water column have the potential to impact Southeast Alaska marine ecosystem dynamics and the productivity of important regional fisheries by altering key prey resources and trophic interactions.Received December 2, 2011; accepted May 9, 2012

Reassessment of spiny dogfish Squalus acanthias age and growth using vertebrae and dorsal‐fin spines

Male and female spiny dogfish Squalus acanthias were collected in the western North Atlantic Ocean in the Gulf of Maine between July 2006 and June 2009. Squalus acanthias ranged from 25 to 102 cm stretch total length and were caught during all months of the year except January. Age estimates derived from banding patterns visible in both the vertebrae and second dorsal-fin spines were compared. Vertebral growth increments were visualized using a modified histological staining technique, which was verified as appropriate for obtaining age estimates. Marginal increment analysis of vertebrae verified the increment periodicity, suggesting annual band deposition. Based on increased precision and accuracy of age estimates, as well as more biologically realistic parameters generated in growth models, the current study found that vertebrae provided a more reliable and accurate means of estimating age in S. acanthias than the second dorsal-fin spine. Age estimates obtained from vertebrae ranged from <1 year-old to 17 years for male and 24 years for female S. acanthias. The two-parameter von Bertalanffy growth model fit to vertebrae-derived age estimates produced parameters of L∞ = 94·23 cm and k = 0·11 for males and L∞ = 100·76 cm and k = 0·12 for females. While these growth parameters differed from those previously reported for S. acanthias in the western North Atlantic Ocean, the causes of such differences were beyond the scope of the current study and remain to be determined.

Lipid correction model of carbon stable isotopes for a cosmopolitan predator, spiny dogfish Squalus acanthias

Three lipid correction models were evaluated for liver and white dorsal muscle from Squalus acanthias. For muscle, all three models performed well, based on the Akaike Information Criterion value corrected for small sample sizes (AIC(c) ), and predicted similar lipid corrections to δ(13) C that were up to 2.8 ‰ higher than those predicted using previously published models based on multispecies data. For liver, which possessed higher bulk C:N values compared to that of white muscle, all three models performed poorly and lipid-corrected δ(13) C values were best approximated by simply adding 5.74 ‰ to bulk δ(13) C values.

Development and observations of a spiny dogfish Squalus acanthias reduction device in a raised footrope silver hake Merluccius bilinearis trawl

A spiny dogfish Squalus acanthias excluder grate (grid) within the extension of a silver hake (whiting) Merluccius bilinearis trawl net was designed and tested in Massachusetts Bay, USA between October 2008 and August 2009 using a live-fed underwater video camera. Grates with 50 mm spacing were investigated for effects from color (white or black), angle, and direction (leading to a top or bottom escape vent). Spiny dogfish numbers were greatly reduced for all gear configurations based on video observations and data collected from the codend, while target species were caught in commercial quantities. Four tows (of various gear configurations) resulted in spiny dogfish blockages in front of the grate. The reduction of spiny dogfish led to increases in the quality of marketable catches, likely reductions in non-target species mortality, and decreases in the codend catch handling times.

Maturity, reproductive cycle and fecundity of the spiny dogfish Squalus acanthias (Chondrichthyes: Squalidae) off the Languedocian coast (southern France, northern Mediterranean)

The spiny dogfish Squalus acanthias is widely distributed in Atlanto-Mediterranean regions, being captured off the Languedocian coast (southern France, northern Mediterranean), despite a decline of landings. The male and female sexually matured between 635–700 mm and 860–880 mm total length (TL), respectively. The largest male and female were 800 mm and 1110 mm TL, respectively and weighed 2220 g and 8900 g, respectively. There was a significant relationship for total mass versus TL, and liver mass versus TL between males and females. The diameter of the largest yolky oocytes ranged between 43 and 47 mm (mean 45.08 ± 0.98), while the mass ranged between 29.5 and 37.4 g (mean 31.79 ± 2.20). Near- term embryos ranged from 245 to 271 mm TL (mean: 258.85 ± 7.28) and weighed from 47.5 to 55.9 g (mean 53.35 ± 2.26). Ovarian fecundity ranged from 6 to 15 (mean = 10.38 ± 2.66). Uterine fecundity or litter size ranged from 4 to 12 (mean = 8.15 ± 2.07). Both fecundities showed a positive relationship with TL of females. A chemical balance of development based on mean dry masses of yolky oocytes and near-term embryos was 0.87 and suggested that S. acanthias is a pure lecithotrophic species. Hepatosomatic index (HSI) and gonadosomatic index (GSI) significantly increased with size in both males and females. HSI reached the highest values in both sub-adult and adult specimens, reflecting the role of the liver in the gonadal production as well as in buoyancy, while in the GSI the highest values were observed in pregnant females. Vitellogenesis proceeds in parallel with embryonic development. Near-term females were captured in different months of the year while a short period of resting could not be excluded between parturition and the beginning of a new pregnancy, so it appears difficult to delineate the length of gestation. However, a reproductive cycle with a wide range from 18 to 24 months remains a suitable hypothesis.

Age and growth of spiny dogfish Squalus acanthias (Squalidae, Chondrichthyes) in pacific waters off the Kuril Islands

On the basis of materials collected from catches of drift salmon nets in Pacific waters off the Kuril Islands from 2005 to 2006, the age and rate of growth of spiny dogfish Squalus acanthias are considered. Individuals with a length of 67–123 cm and weight of 1140–5970 g aged 10–26 years were represented in catches. In almost all age classes, the length of males was greater and the weight smaller than in females. The lifespan of females is slightly higher as compared to males-26 and 25 years, respectively. The values of K coefficient of the Bertallanffi equation of growth in males and females comprised 0.10 and 0.05 and the calculated values of the asymptotic body length comprised 116.3 cm and 147.2 cm. A relationship was found between the age of spiny dogfish and the spine size: its length (rs = 0.693), base width (rs = 0.815), and base length (rs = 0.823).

Use of satellite tags to reveal the movements of spiny dogfish Squalus acanthias in the western North Atlantic Ocean

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 418:249-254 (2010) - DOI: https://doi.org/10.3354/meps08821 NOTE Use of satellite tags to reveal the movements of spiny dogfish Squalus acanthias in the western North Atlantic Ocean James A. Sulikowski1,*, Benjamin Galuardi2, Walter Bubley3, Nathan B. Furey1, William B. Driggers III4, G. Walter Ingram Jr.4, Paul C. W. Tsang3 1Marine Science Center, University of New England, 11 Hills Beach Rd, Biddeford, Maine 04005, USA 2Large Pelagics Research Center, Room 177, Spaulding Hall, University of New Hampshire, 46 College Rd, Durham, New Hampshire 03824, USA 3Department of Molecular, Cellular and Biomedical Sciences, Kendall Hall, University of New Hampshire, 129 Main Street, Durham, New Hampshire 03824, USA 4National Marine Fisheries Center, Southeast Fisheries Science Center, Mississippi Laboratories, PO Drawer 1207, Pascagoula, Mississippi 39568, USA *Email: jsulikowski@une.edu ABSTRACT: The use of popup satellite archival transmitting tags (PSAT) has helped to reveal horizontal and vertical movements of large, highly migratory fishes to assist in the management of their stocks. We tested the efficacy of a significantly smaller satellite tag, the X-tag, to track the movements of 3 spiny dogfish Squalus acanthias in the western North Atlantic Ocean. Tag retention rates for this study ranged between 65 and 189 d. The sharks occupied waters with temperatures ranging from 5.2 to 14.9°C and had estimated average horizontal speeds between 1.36 and 2.49 km h–1. The sharks initially moved east into offshore waters after tagging in the Gulf of Maine and then into southern waters off the coast of New Jersey, USA. Diel depth patterns indicated that each shark was equally active during both day and night. Our results suggest that spiny dogfish are more mobile, both vertically and horizontally, than previously thought and that smaller PSATs can provide useful information on the movement patterns of a relatively small species of shark. KEY WORDS: Spiny dogfish · Movement · Depth preferences · Tracking Full text in pdf format PreviousNextCite this article as: Sulikowski JA, Galuardi B, Bubley W, Furey NB, Driggers WB III, Ingram GW Jr, Tsang PCW (2010) Use of satellite tags to reveal the movements of spiny dogfish Squalus acanthias in the western North Atlantic Ocean. Mar Ecol Prog Ser 418:249-254. https://doi.org/10.3354/meps08821Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 418. Online publication date: November 18, 2010 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2010 Inter-Research.

Frequency of Multiple Paternity in the Spiny Dogfish Squalus acanthias in the Western North Atlantic

Multiple paternity (MP) has been shown to be widespread in elasmobranch fishes although its prevalence and the number of sires per litter vary considerably among species. In the squaloid shark Squalus acanthias, MP has been reported, but whether it is a common feature of the species' reproductive strategy is unknown. In this study, we determined the frequency of MP in 29 litters of S. acanthias sampled from the lower Chesapeake Bay and coastal Virginia waters, using 7 highly polymorphic nuclear DNA microsatellite loci. Only 5 litters (17% of the total) were genetically polyandrous, with at least 2 sires per litter. Litter size increased with female size but was similar between polyandrous and monandrous females.

Pairwise modulation of jaw muscle activity in two species of elasmobranchs

Most studies of the function of feeding muscles in fish have implanted electromyogram electrodes unilaterally to understand the motor pattern associated with a behavior. The few studies that have implanted bilaterally have found that paired muscles may be activated asynchronously, often resulting in visible kinematic asymmetry. We investigated modulation of pairwise asynchrony (modulation in the activation patterns of left and right members of a muscle) of feeding muscles during capture and processing of two types of prey in spiny dogfish Squalus acanthias and little skates Leucoraja erinacea (Elasmobranchii). Two asynchrony indices quantified the degree to which muscles in a pair were activated out of phase (lag index, AIlag )a nd the degree to which durations differ (duration index, AIdur). Feeding behaviors for both species were compared according to these indices and total event duration using principal components analysis. Both species modulated pairwise asynchrony according to prey type, exhibiting more asynchronous motor patterns when feeding on more complex prey items (those requiring more processing); however, the motor patterns underlying this asynchrony differed between species. Dogfish process complex prey using head-shaking, which requires alternating activation of contralateral head muscles (i.e. high lag index value). In contrast, little skates process complex prey using a completely unilateral behavior in which prey is moved to one corner of the jaws and jaw muscles are activated on that side only (i.e. high duration index value). Asynchronous behaviors are not detected by unilateral implants; our data demonstrate the importance of bilateral implantation to identify fine details of feeding motor patterns, particularly those involving complex prey.

Subtropical migrants in the southwestern part of the Bering Sea

From 2003 to 2008, arrivals (including mass) of sea bream Brama japonica, saury Cololabis saira, and spiny dogfish Squalus acanthias, as well as some cases of catches of Japanese anchovy Engraulis japonicus, and Todarodes pacificus, and Onychoteuthis borealijaponica squids were recorded in Pacific waters of Kamchatka in the southwestern sector of the Bering Sea. The penetration of these species far to the north is related to feeding migrations as well as to the passive transfer of water by currents. Migrations of subtropical species to Pacific waters of Kamchatka and the southern part of the Bering Sea depend on thermal conditions and circulation of currents in each particular year and are determined, first of all, by the intensity of the Western Subarctic gyre, although in some years, the migration flow of B. japonica and C. saira from the northeastern part of the Pacific Ocean increases.

Recent incidental catch of sharks in gillnet fisheries of Newfoundland and Labrador, Canada

ESR Endangered Species Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials ESR 11:133-146 (2010) - DOI: https://doi.org/10.3354/esr00268 Recent incidental catch of sharks in gillnet fisheries of Newfoundland and Labrador, Canada Steven Benjamins1,*, David W. Kulka2,3, Jack Lawson2 1Dept. of Zoology, University of Otago, PO Box 56, Dunedin, New Zealand 2Fisheries and Oceans Canada, PO Box 5667, St. John’s, Newfoundland and Labrador, A1C 5X1, Canada 3Present address: 50 Fernlilly Place, Waverley, Nova Scotia B2R 1X2, Canada *Email: stevenbenjamins@yahoo.com ABSTRACT: Waters of Newfoundland and Labrador, Canada, are home to a variety of shark species, many of which have been previously reported as incidental catch in several gillnet fisheries. However, defensible estimates of incidental catch rates are unavailable. This mortality is of concern, given reports of considerable declines in abundance of several large shark species in this area. On the basis of several data sources (incidental catch rates derived using different methods of reporting; fish landings and net days as measures of effort, with fishing trips as sampling units), the total numbers of incidentally caught sharks were estimated in 8 gillnet fisheries for 2001, 2002, and 2003. Confidence intervals were estimated using resampling techniques. Most fisheries reported incidental catch of some sharks, although there were distinct differences between different fisheries in diversity and abundance of species encountered. Spiny dogfish Squalus acanthias was the most commonly captured species, occurring in various fisheries along the south coast of the island of Newfoundland. Large sharks, including basking shark Cetorhinus maximus, shortfin mako Isurus oxyrinchus, porbeagle Lamna nasus, and blue shark Prionace glauca, were reported in small numbers in all fisheries. Deepwater fisheries targeting e.g. Greenland halibut Reinhardtius hippoglossoides caught mainly sharks of the continental slope, such as Greenland shark Somniosus microcephalus, black dogfish Centroscyllium fabricii, and several other deepwater species. Catch rates of several species appear high and may warrant conservation action. For the majority, however, there is insufficient information on abundance, and sometimes even basic biology, to accurately assess the impact of this incidental mortality. KEY WORDS: Sharks · Incidental catch · Bycatch · Canada · Northwest Atlantic · Mortality · Dogfish · Gillnets Full text in pdf format PreviousNextCite this article as: Benjamins S, Kulka DW, Lawson J (2010) Recent incidental catch of sharks in gillnet fisheries of Newfoundland and Labrador, Canada. Endang Species Res 11:133-146. https://doi.org/10.3354/esr00268 Export citation Mail this link - Contents Mailing Lists - RSS Facebook - Tweet - linkedIn Cited by Published in ESR Vol. 11, No. 2. Online publication date: April 07, 2010 Print ISSN: 1863-5407; Online ISSN: 1613-4796 Copyright © 2010 Inter-Research.