Biology and Management of Dogfish Sharks

2009 ◽  
Keyword(s):  
Spiny Dogfish ◽  
Total Biomass ◽  
Trawl Survey ◽  
Shark Species ◽  
Depth Range ◽  
The European Union ◽  
Northern Adriatic Sea ◽  
Western Basin ◽  
Elasmobranch Species ◽  
Elasmobranch Fishes

Abstract.—Data on two shark species, collected in the frame of the European Union program Mediterranean International Trawl Survey Program, are analyzed and reported. Indices of summer abundance per standardized area (per km2) in weight and number are available for both species since 1994 along the European Mediterranean coasts (from the Alboran to the Aegean seas). The studied area, with depths ranging from 10 to 800 m, was divided into five depth strata. Data of 10,000 hauls were analyzed and 44 elasmobranch species identified. The estimated comprehensive standing biomass of elasmobranch fishes within the explored area was 55,000 mt (mt); spiny dogfish <em>Squalus acanthias </em>was one of the most abundant species with an estimated biomass of 6,700 mt, while longnose spiny dogfish <em>S. blainvillei</em>, with about 1,500 mt, represents only 3% of the total biomass. The mean density of spiny dogfish was significantly different between the Mediterranean eastern basin (22.7 kg/km2) and western basin (only 0.8 kg/km2). On the contrary, longnose spiny dogfish shows higher density in the western basin (6.6 kg/km2) than in the eastern one (1.7 kg/km2). However, the spatial distribution of both species is fairly confined; spiny dogfish was caught in only 5% of the tows and longnose spiny dogfish in 3%. Even if the depth range of presence for both species spreads from less than 50 m to more than 700 m, the abundance indexes suggest a major presence in the coastal areas for spiny dogfish. This statement is based primarily on the high densities of the mentioned species in shallow waters of the northern Adriatic Sea; elsewhere the main concentrations are always positioned in the 200–500 m depth range.

scholarly journals CURRENT DATA ON COMPOSITION AND DISTRIBUTION OF TRAWL MACROZOOBENTHOS IN THE RUSSIAN WATERS OF THE JAPAN SEA

2018 ◽  
Vol 193 ◽  
pp. 33-49 ◽  
Author(s):  
N. V. Kolpakov ◽  
I. A. Korneichuk ◽  
V. A. Nadtochy
Keyword(s):  
Peter The Great Bay ◽  
Japan Sea ◽  
Snow Crab ◽  
Total Biomass ◽  
Trawl Survey ◽  
Depth Range ◽  
Sea Stars ◽  
Southern Primorye ◽  
The Japan Sea ◽  
Average Biomass

The bottom trawl survey (430 stations) was conducted over the shelf and continental slope in the Russian sector of the Japan Sea (total depth range 10–750 m) on April 1 — July 8, 2015. In total, 211 taxa of invertebrates were recorded in the trawl catches. Most of them belonged to sea stars (36), shrimps (32), gastropods (27), bivalves (23), crabs and craboids (11), polychaetes (11), coral polyps (10), and sponges (10). The total biomass of macrozoobenthos in the surveyed area was assessed as 1572.5 . 103 t (136.6 . 103 t in Peter the Great Bay, 341.5 . 103 t at southern Primorye, 686.0 . 103 t at northern Primorye, and 408.4 . 103 t at western Sakhalin) that was higher than the mean long-term level. The total stock of commercial invertebrates was assessed as 630.0 . 103 t. Its highest portion (265.2 . 103 t or 42.1 %) was concentrated in the western Tatar Strait. The average biomass of macrozoobenthos was 13.5 ± 1.1 g/m2 , including 6.3 ± 0.5 g/m2 of commercial species. The most abundant groups were basket stars (372.2 . 103 t), crabs (231.6 . 103 t), shrimp (226.9 . 103 t), sponges (182.9 . 103 t), sea lilies (167.5 . 103 t), sea stars (77.2 . 103 t), sea urchins (59.0 . 103 t), craboids (48.7 . 103 t), and bivalves (49.5 . 103 t). Vertical distribution of both total and commercial benthos was distinguished by peaks on the upper shelf (10–50 m) and upper slope (300–400 m). Over the surveyed northern Japan Sea waters, 18 biocoenotic complexes of trawl macrozoobenthos were identified. The largest area was occupied by the complex of immobile sestonophagous sea lily Heliometra glacialis (131 stations in the depth range of 104–692 m with average biomass 5.5 g/m2 ), other wide-spread complexes were those of polyphagous snow crab Chionoecetes opilio (71 stations, 27–552 m, 4.4 g/m2 ), mobile sestonophagous basket star Gorgonocephalus eucnemis (40 stations, 58–372 m, 6.6 g/m2 ), and polyphagous fawn sea urchin Strongylocentrotus pallidus (40 stations, 17–351 m, 4.7 g/m2 ).

scholarly journals Visual Opsin Diversity in Sharks and Rays

2019 ◽  
Vol 37 (3) ◽  
pp. 811-827 ◽  
Author(s):  
Nathan S Hart ◽  
Trevor D Lamb ◽  
Hardip R Patel ◽  
Aaron Chuah ◽  
Riccardo C Natoli ◽  
...  
Keyword(s):  
Color Vision ◽  
Marine Mammals ◽  
Shark Species ◽  
Marine Predators ◽  
Cone Opsin ◽  
Aquatic Vertebrates ◽  
Elasmobranch Species ◽  
Spectral Absorbance ◽  
Elasmobranch Fishes ◽  
Cone Opsins

Abstract The diversity of color vision systems found in extant vertebrates suggests that different evolutionary selection pressures have driven specializations in photoreceptor complement and visual pigment spectral tuning appropriate for an animal’s behavior, habitat, and life history. Aquatic vertebrates in particular show high variability in chromatic vision and have become important models for understanding the role of color vision in prey detection, predator avoidance, and social interactions. In this study, we examined the capacity for chromatic vision in elasmobranch fishes, a group that have received relatively little attention to date. We used microspectrophotometry to measure the spectral absorbance of the visual pigments in the outer segments of individual photoreceptors from several ray and shark species, and we sequenced the opsin mRNAs obtained from the retinas of the same species, as well as from additional elasmobranch species. We reveal the phylogenetically widespread occurrence of dichromatic color vision in rays based on two cone opsins, RH2 and LWS. We also confirm that all shark species studied to date appear to be cone monochromats but report that in different species the single cone opsin may be of either the LWS or the RH2 class. From this, we infer that cone monochromacy in sharks has evolved independently on multiple occasions. Together with earlier discoveries in secondarily aquatic marine mammals, this suggests that cone-based color vision may be of little use for large marine predators, such as sharks, pinnipeds, and cetaceans.

scholarly journals Ichthyofauna in an estuary of the Mataripe area, Todos os Santos Bay, Bahia, Brazil

2011 ◽  
Vol 59 (1) ◽  
pp. 75-95 ◽  
Author(s):  
June Ferraz Dias ◽  
Aline Mariane Gonçalves ◽  
Wellington Silva Fernandez ◽  
Helcy Lylian Nogueira Silbiger ◽  
Carla Bertolucci Fiadi ◽  
...  
Keyword(s):  
Great Majority ◽  
Population Level ◽  
Oil Refinery ◽  
Fishing Gear ◽  
Total Biomass ◽  
Study Region ◽  
Structure And Dynamics ◽  
Growth Area ◽  
Elasmobranch Species ◽  
Estuarine Region

The community structure and dynamics as well as some biological parameters of selected species of the ichthyofauna of the Mataripe estuarine region affected by the Landulfo Alves Oil Refinery (RLAM) were analyzed. Twenty stations were sampled with a gillnet in five different periods: August and December 2003, March and July/August 2004 and January 2005. Thirty-five actinopterygian species and one elasmobranch species were recorded, Oligoplites saurus, Diapterus rhombeus, Lutjanus synagris and Scomberomorus brasiliensis among them, on all the campaigns. A total of 1368 specimens, weighing 36.10 kg, were caught. The ichthyofauna total biomass was greater, in weight, on the eastern side of the study region, especially at the stations close to the shoals/reefs and the rocky bottom. A similar pattern was also observed for the diversity values. In general, low evenness and diversity were observed in the area studied, possibly as a result of the fishing gear used. D. rhombeus juveniles dominated in all but one of the samplings (July 2004), in which latter Cyclichthys spinosus was dominant. Carangids and species associated with consolidated bottoms were observed, although in small numbers, throughout the study period. In spite of the limitations imposed by the gear used for sampling, the estuarine area influenced by the RLAM was seen to play a role as a growth area for the great majority of species, especially the mojarra (D. rhombeus), but it offers no fishing potential due to the prevalence of young and small individuals. Evidence of imminent spawning was recorded for Pomadasys corvinaeformis in August 2003, and recent spawning in March 2004 for Oligoplites saurus. Further, mature individuals occurred in insufficient numbers to permit population level evaluation.

Tapeworm discovery in elasmobranch fishes: quantifying patterns and identifying their correlates

2020 ◽  
Vol 71 (1) ◽  
pp. 78 ◽  
Author(s):  
Haseeb S. Randhawa ◽  
Robert Poulin
Keyword(s):  
Host Species ◽  
Time Lag ◽  
Mixed Effects ◽  
Mixed Effects Models ◽  
Linear Mixed Effects Models ◽  
Linear Mixed Effects ◽  
Factors Influencing ◽  
Elasmobranch Species ◽  
Elasmobranch Fishes ◽  
Latitudinal Range

Most parasites from known host species are yet to be discovered and described, let alone those from host species not yet known to science. Here, we use tapeworms of elasmobranchs to identify factors influencing their discovery and explaining the time lag between the descriptions of elasmobranch hosts and their respective tapeworm parasites. The dataset included 918 tapeworm species from 290 elasmobranch species. Data were analysed using linear mixed-effects models. Our findings indicated that we are currently in the midst of the greatest rate of discovery for tapeworms exploiting elasmobranchs. We identified tapeworm size, year of discovery of the type host, host latitudinal range and type locality of the parasite influencing most on the probability of discovery of tapeworms from elasmobranchs and the average time lag between descriptions of elasmobranchs and their tapeworms. The time lag between descriptions is decreasing progressively, but, at current rates and number of taxonomic experts, it will take two centuries to clear the backlog of undescribed tapeworms from known elasmobranch species. Given that the number of new elasmobranch species described each year is on the rise, we need to re-assess funding strategies to save elasmobranchs (and, thus, their tapeworm parasites) before they go extinct.

Abundance of demersal fish resources in the Persian Gulf and Oman Sea

2006 ◽  
Vol 86 (6) ◽  
pp. 1455-1462 ◽  
Author(s):  
T. Valinassab ◽  
R. Daryanabard ◽  
R. Dehghani ◽  
G.J. Pierce
Keyword(s):  
Persian Gulf ◽  
Central Area ◽  
Demersal Fish ◽  
Total Biomass ◽  
Trawl Survey ◽  
Important Species ◽  
Fish Resources ◽  
Oman Sea ◽  
Commercially Important ◽  
The Persian Gulf

We report on results of a trawl survey during 2003–2004 to assess the abundance of demersal fish resources in the Persian Gulf and Oman Sea. Samples were taken at a total of 316 trawl stations selected following a stratified random procedure. Catch rates (catch per unit area, CPUA) and total biomass were estimated. Total demersal fish biomass was estimated to be approximately 73,000 tonnes in Persian Gulf waters and approximately 39,000 tonnes in the Oman Sea. The lowest CPUA was recorded in the west of the study area (stratum A, approximately 1700 kg/n.m.2) and the highest in the east (stratum Q, 13943.4 kg/n.m.2), although density of commercially important species was higher in the central area (stratum K). Catch rate and biomass varied significantly in relation to seabed depth. Commercially important demersal species made up around 60% of the estimated total biomass. The most abundant species groups were rays, catfish, grunts, nemipterids and carangids. Several important species (e.g. silver pomfret, croakers and sharks) appear to have declined since the late 1970s while others, such as rays and catfish, have increased.

Influence of environmental, spatial, and ontogenetic variables on habitat selection and management of spiny dogfish in the Northeast (US) shelf large marine ecosystem

2014 ◽  
Vol 71 (4) ◽  
pp. 567-580 ◽  
Author(s):  
Skyler R. Sagarese ◽  
Michael G. Frisk ◽  
Thomas J. Miller ◽  
Kathy A. Sosebee ◽  
John A. Musick ◽  
...  
Keyword(s):  
Habitat Selection ◽  
Environmental Conditions ◽  
Statistical Power ◽  
Stock Assessment ◽  
Marine Ecosystem ◽  
Spiny Dogfish ◽  
Trawl Survey ◽  
Science Center ◽  
Large Marine Ecosystem ◽  
Northeast Us

Declines in abundance of commercially valuable groundfish have highlighted the ecological and commercial importance of previously underutilized elasmobranchs in the Northeast (US) shelf large marine ecosystem (NES LME). Seasonal distributions and ontogenetic habitats of one such species, spiny dogfish (Squalus acanthias), were investigated using Northeast Fisheries Science Center (NEFSC) bottom trawl survey data (1963–2009). Neonate, immature, and mature dogfish all selected warmer, more saline, and more southerly locations during spring compared with available locations. During autumn, larger dogfish occupied relatively warmer, shallower, and less saline waters while neonates selected higher salinities. There were strong ontogenetic patterns in habitats occupied. Contrary to expectation, geographic range contracted as abundance increased during autumn. This suggests that niche constraints override density-dependent effects, although detection of relationships within stages was limited by low statistical power. The proportion of mature female survey catch within the Mid-Atlantic Bight was significantly related to temperature, suggesting that environmental conditions surveyed may impact population trends. Collectively, these results highlight critical habitats, suggest mechanisms behind ontogenetic habitat selection, and provide insight into how changing environmental conditions may impact stock assessment.

scholarly journals Bayesian spatial multispecies modelling to assess pelagic fish stocks from acoustic- and trawl-survey data

2012 ◽  
Vol 69 (1) ◽  
pp. 95-104 ◽  
Author(s):  
Teppo Juntunen ◽  
Jarno Vanhatalo ◽  
Heikki Peltonen ◽  
Samu Mäntyniemi
Keyword(s):  
Spatial Distribution ◽  
Survey Data ◽  
Spatial Model ◽  
Pelagic Fish ◽  
Clupea Harengus ◽  
Environmental Data ◽  
Total Biomass ◽  
Trawl Survey ◽  
Linear Predictor ◽  
Fish Stocks

Abstract Juntunen, T., Vanhatalo, J., Peltonen, H., and Mäntyniemi, S. 2012. Bayesian spatial multispecies modelling to assess pelagic fish stocks from acoustic- and trawl-survey data. – ICES Journal of Marine Science, 69: 95–104. A Bayesian spatial model was constructed to estimate the abundance of multiple fish species in a pelagic environment. Acoustic- and trawl-survey data were combined with environmental data to predict the spatial distribution of (i) the acoustic backscattering of fish, (ii) the relative proportion of each species, and (iii) their mean length in the Gulf of Finland in the northeastern Baltic Sea. By combining the three spatial model layers, the spatial distribution of the biomass of each species was estimated. The model consists of a linear predictor on environmental variables and a spatial random effect given by a Gaussian process. A Bayesian approach is a natural choice for the task because it provides a theoretically justified means of summarizing the uncertainties from various model layers. In the study area, three species dominate pelagic waters: sprat (Sprattus sprattus), herring (Clupea harengus), and three-spined stickleback (Gasterosteus aculeatus). Results are presented for each model layer and for estimated total biomass for each species in 2 × 2 km lattices. The posterior mean and central 95% credible intervals of total biomass were sprat 45.7 kt (27.7–71.6), herring 24.6 kt (9.7–41.3), and three-spined stickleback 1.9 kt (0.9–3.2).

Range of electrosensory detection of prey by Carcharhinus melanopterus and Himantura granulata

2001 ◽  
Vol 52 (3) ◽  
pp. 291 ◽  
Author(s):  
Olivia S. Haine ◽  
Peter V. Ridd ◽  
Richard J. Rowe
Keyword(s):  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Decay Rates ◽  
Spatial Context ◽  
Prey Detection ◽  
Elasmobranch Species ◽  
Electric Potentials ◽  
Elasmobranch Fishes ◽  
Carcharhinus Melanopterus

Elasmobranch fishes have a well developed electrosense that is used for prey detection. Research into the nature of bioelectric cues emitted by prey has, however, been neglected, and consequently the spatial context in which the electrosense operates to detect and home in on prey is not completely understood. This study provided data on both ac and dc electric potentials produced by teleost, crustacean and bivalve prey, as well as measured the decay rates of electric field strength with distance. The electrosensitivity of two tropical elasmobranch species was calculated to be ~4 nV cm–1, from which it was calculated that these predators probably detect their prey at a range of ~0. 25 m.

scholarly journals Species composition and distribution of fishes and prawns in the Amur River channel

2020 ◽  
Vol 200 (2) ◽  
pp. 292-307
Author(s):  
V. N. Koshelev ◽  
N. V. Kolpakov
Keyword(s):  
Fish Species ◽  
Total Biomass ◽  
Trawl Survey ◽  
Amur River ◽  
Commercial Fish ◽  
The Amur River ◽  
Bottom Fish ◽  
Main Portion ◽  
Beam Trawl Survey ◽  
Species Composition And Distribution

istribution of fishes and prawns in the Amur River (40–960 km from the mouth) is described on results of the beam-trawl survey conducted in September-October, 2003 (57 trawl stations at the depth of 1.5–23.0 m). In total, 2584 ind. of 22 fish species and 1077 ind. of 1 invertebrate species (prawn Palaemon modestus) were caught. The highest species richness was registered for orders Cypriniformes (13 species) and Siluriformes (4 species). The fish and prawn stocks were evaluated as 32.161 . 106 ind. (583.8 t) for bottom and near-bottom fish and 4.887 . 106 ind. (8.8 t) for prawns. Two commercial fish species were the most abundant: catfishes Tachysurus brashnikowi (16.26 . 106 ind. or 32.9 % of total biomass) and T. sinensis (4.32 . 106 ind. or 24.0 % of total biomass); other 6 fish species with considerable biomass were lizard gudgeon Saurogobio dabryi (12.6 %), ussuri catfish T. ussuriensis (9.7 %), amur white-pinned gudgeon Romanogobio tenuicorpus (7.8 %), amur sturgeon Acipenser schrenckii (5.6 %), amur gudgeon Gobio cynocephalus (2.4 %), and kaluga Huso dauricus (0.6 %). Distribution density varied in the range of 0.01–2.57 g/m2 (on average 0.45 ± 0.27 g/m2) for fish and 0.005–0.044 g/m2 (0.021 ± 0.012 g/m2) for prawns. Abundance of both fish and prawns increased multifold towards the Amur mouth that correlated with increasing of forage benthos biomass in the same direction. So, the main portion of fish biomass (82.4 %) was distributed in the Amur River downstream (40–400 km from the mouth) and the prawn stock was concentrated completely in its lowermost part (50–150 km from the mouth).

Variation in behavioural responses of sub-tropical marine fishes to experimental longline capture

2020 ◽  
Author(s):  
Brendan S Talwar ◽  
Ian A Bouyoucos ◽  
Edward J Brooks ◽  
Jacob W Brownscombe ◽  
Cory D Suski ◽  
...  
Keyword(s):  
Physiological Stress ◽  
Behavioural Response ◽  
Shark Species ◽  
The Bahamas ◽  
Behavioural Responses ◽  
Capture Event ◽  
Physiological Stress Response ◽  
Elasmobranch Species ◽  
Quadratic Response ◽  
Nurse Sharks

Abstract Fishes are often caught as bycatch on longlines and subsequently discarded. The behavioural response of fishes to longline capture is poorly understood, although it may be linked to the magnitude of the physiological stress response, and, ultimately, contribute to stress-induced mortality. We used accelerometers, video cameras, and hook timers to analyse the behavioural response of 13 subtropical teleost and elasmobranch species to experimental longline capture in The Bahamas. We found that, across all species and species groups, fight intensity during a capture event was best described by a negative linear and positive quadratic response. Nurse sharks and tiger sharks had lower fight intensity values and exhibited less steepness in their quadratic response during the first 10 min of capture than other species, particularly blacktip and Caribbean reef sharks. Nurse sharks also exhibited the most consistent fight intensity during the entire capture event compared to other shark species, particularly the blacknose shark. Generally, obligate ram ventilators and mixed ventilators exhibited higher steepness in fight intensity trajectories than buccal/spiracular pumpers, which had more consistent, lower fight intensity values. Behavioural responses to longline capture are species specific but may be linked to distinct evolutionary traits such as respiratory mode.

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