The calls of gadoid fish

1978 ◽  
Vol 58 (4) ◽  
pp. 891-911 ◽  
Author(s):  
A. D. Hawkins ◽  
Knud Just Rasmussen
Keyword(s):  
Pulse Repetition Rate ◽  
Gadus Morhua ◽  
Temporal Structure ◽  
Low Frequency ◽  
Melanogrammus Aeglefinus ◽  
Additional Species ◽  
European Species ◽  
Northern European ◽  
Frequency Spacing ◽  
Behavioural Significance

Of nine northern European species of the Gadidae examined in the aquarium, or in cages in the sea, four produced sounds. The vocal species were the haddock, Melanogrammus aeglefinus (L.); the cod, Gadus morhua L.; the lythe, Pollachius pollachius (L.); and the tadpole-fish, Raniceps raninns (L.). The main differences between the calls of the vocal species lay in their temporal structure, all the calls being divisible into brief pulses of low frequency sound, repeated at different rates and in different groupings. Calls with this structure yielded spectra with a series of spaced harmonics, the frequency spacing depending upon the pulse repetition rate.Sixteen additional species were dissected, and seven of these showed well developed muscles attached to the swimbladder, similar to those found in the four vocal species. The remaining nine species, together with the five non-vocal species examined in the aquarium, lacked the muscles.The behavioural significance of the calls and the operation of the sound producing mechanism are discussed.

Recruitment to Northwest Atlantic Cod (Gadus morhua) and Haddock (Melanogrammus aeglefinus) Stocks: Influence of Stock Size and Climate

1987 ◽  
Vol 44 (1) ◽  
pp. 26-39 ◽  
Author(s):  
J. Anthony Koslow ◽  
Keith R. Thompson ◽  
William Silvert
Keyword(s):  
Large Scale ◽  
Gadus Morhua ◽  
Reproductive Output ◽  
Atlantic Cod ◽  
Low Frequency ◽  
Melanogrammus Aeglefinus ◽  
Northwest Atlantic ◽  
Biological Variables ◽  
Low Frequency Variability ◽  
Haddock Melanogrammus Aeglefinus

Year-class success of both Atlantic cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) stocks in the northwest Atlantic exhibits large-scale coherence and low-frequency variability with apparent periodicities of 10–20 yr. Several physical and biological variables in the region exhibit similar large-scale coherence and apparent periodicity. Multiple regression analysis indicates that year-class success in northwest Atlantic cod stocks tends to be associated with large-scale meteorological patterns and offshore winds. Recruitment to most haddock stocks from the Scotian Shelf to Georges Bank is negatively associated with abundance of 0-group mackerel, which may be due to predation over winter and/or to a combination of environmental features including sea-surface temperature, large-scale atmospheric pressure systems, and freshwater outflows. Statistical analyses often did not define a unique set of variables that best predicted fishery recruitment due to widespread intercorrelations among environmental processes and the likelihood that not all relevant processes entered directly into the analyses. There is little evidence that stock reproductive output during the study period was significantly related to year-class success.

Parasites as biological tags in marine fisheries research: European Atlantic waters

Parasitology ◽  
2014 ◽  
Vol 142 (1) ◽  
pp. 54-67 ◽  
Author(s):  
K. MACKENZIE ◽  
W. HEMMINGSEN
Keyword(s):  
Marine Mammals ◽  
Gadus Morhua ◽  
Clupea Harengus ◽  
Melanogrammus Aeglefinus ◽  
Ecological Group ◽  
The North ◽  
Recent Developments ◽  
Host Parasite ◽  
Mediterranean And Black Seas ◽  
Biological Tags

SUMMARYStudies of the use of parasites as biological tags for stock identification and to follow migrations of marine fish, mammals and invertebrates in European Atlantic waters are critically reviewed and evaluated. The region covered includes the North, Baltic, Barents and White Seas plus Icelandic waters, but excludes the Mediterranean and Black Seas. Each fish species or ecological group of species is treated separately. More parasite tag studies have been carried out on Atlantic herring Clupea harengus than on any other species, while cod Gadus morhua have also been the subject of many studies. Other species that have been the subjects of more than one study are: blue whiting Micromesistius poutassou, whiting Merlangius merlangus, haddock Melanogrammus aeglefinus, Norway pout Trisopterus esmarkii, horse mackerel Trachurus trachurus and mackerel Scomber scombrus. Other species are dealt with under the general headings redfishes, flatfish, tunas, anadromous fish, elasmobranchs, marine mammals and invertebrates. A final section highlights how parasites can be, and have been, misused as biological tags, and how this can be avoided. It also reviews recent developments in methodology and parasite genetics, considers the potential effects of climate change on the distributions of both hosts and parasites, and suggests host-parasite systems that should reward further research.

scholarly journals Population dynamics of two sympatric intertidal fish species (the shanny, Lipophrys pholis and long-spined scorpion fish, Taurulus bubalis) of Great Britain

2016 ◽  
Vol 98 (3) ◽  
pp. 589-595 ◽  
Author(s):  
C.J. Barrett ◽  
M.L. Johnson ◽  
S.L. Hull
Keyword(s):  
Population Dynamics ◽  
Great Britain ◽  
Fish Species ◽  
Gadus Morhua ◽  
Sympatric Species ◽  
Rocky Intertidal ◽  
Melanogrammus Aeglefinus ◽  
Intertidal Zones ◽  
Spatio Temporal ◽  
Scorpion Fish

The shanny/common blenny (Lipophrys pholis) and long-spined scorpionfish/bullhead (Taurulus bubalis) are commonly encountered, sympatric species within much of Great Britain's rocky intertidal zones. Despite being prey items of the cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) respectively, and both contributors to the diet of the near-threatened European otter (Lutra lutra), little is known on the population dynamics of the temperate specimens of Great Britain. It is further less known of the degrees of sympatricity between the two fish species and to what extent they are able to coexist. The current study examines spatio-temporal distributions and abundances at various resolutions: monthly population dynamics of both species along England's Yorkshire coast and seasonal population dynamics along the Yorkshire coast and around the Isle of Anglesey, Wales. Studies of their abundances, sizes, degrees of rock pool co-occurrence and diel activities are further examined, which indicate coexistence is maintained when interspecific co-occurrence takes place only between specimens of similar sizes, thus demoting size-related dominance hierarchies.

Species specific behaviour and catchability of gadoid fish to floated and bottom set pots

2016 ◽  
Vol 74 (3) ◽  
pp. 769-779 ◽  
Author(s):  
Neil Anders ◽  
Anders Fernö ◽  
Odd-Børre Humborstad ◽  
Svein Løkkeborg ◽  
Anne Christine Utne-Palm
Keyword(s):  
Water Column ◽  
Gadus Morhua ◽  
Capture Efficiency ◽  
Escape Rate ◽  
Melanogrammus Aeglefinus ◽  
Encounter Rate ◽  
Specific Behaviour ◽  
Upstream Direction ◽  
Species Specific ◽  
Specific Food

To increase our understanding of the interaction between fish and baited fishing gear we quantitatively described the behaviour of cod (Gadus morhua), saithe (Pollachius virens), and haddock (Melanogrammus aeglefinus) to baited pots in a fjord in northern Norway. Detailed video analyses were made to describe species specific responses and examine the effect of lifting the pot off the bottom. The majority of both cod and saithe approached the pots in an upstream direction, and fish approached floated pots higher in the water column than bottom set pots. Cod tended to approach a pot along the seabed and were more likely to encounter the bottom set pot than the floated pot, whereas saithe more often approached in the water column. The capture efficiency was low for all species, but cod were more likely to be caught than saithe and haddock. Cod showed a high encounter rate, low entrance rate and high escape rate. For saithe, a low encounter rate was the chief factor limiting capture efficiency. The observed differences between cod and saithe were explained by species-specific food-search strategies. No difference in entrance rate, escape rate or catch efficiency between the two pot types were found.

scholarly journals Documentation of multiple species of marine fish trapped in Atlantic salmon sea-cages in Norway

2018 ◽  
Vol 31 ◽  
pp. 31
Author(s):  
Per Gunnar Fjelldal ◽  
Monica F. Solberg ◽  
Kevin A. Glover ◽  
Ole Folkedal ◽  
Jonatan Nilsson ◽  
...  
Keyword(s):  
Atlantic Salmon ◽  
Salmo Trutta ◽  
Gadus Morhua ◽  
Mesh Size ◽  
Anguilla Anguilla ◽  
Wild Fish ◽  
Melanogrammus Aeglefinus ◽  
European Eel ◽  
Farmed Salmon ◽  
Sea Trout

The production of salmonids in sea-cages has been developed for monoculture of the target species. However, we show here for the first time, that wild fish may enter sea-cages used for farming of Atlantic salmon (Salmo salar L.) in Norway, out-grow the mesh size, and thereafter become permanently trapped. Within seven different sea-cages located in western Norway, eight different species of wild fish were identified; European eel (Anguilla anguilla), sea trout (Salmo trutta L.), cod (Gadus morhua), haddock (Melanogrammus aeglefinus), saithe (Pollachius virens), pollack (Pollachius pollachius), hake (Merluccius merluccius) and whiting (Merlangius merlangus). In the two most extreme cases, a 5 × 5 × 7 m cage with 311 farmed salmon (903 g) also contained 542 whiting (79 g), 77 haddock (43 g), and 5 cod (26 g), and a 12 × 12 × 15 m cage with 1695 farmed salmon (559 g) also contained 1196 haddock (35 g), 1115 whiting (31 g), 46 cod (23 g), 23 saithe (48 g), 15 pollock (22 g), 5 sea trout (54 g), and 2 hake (29 g). The present study thus demonstrates that aquaculture cages designed for monoculture may attract and effectively ‘trap’ wild fish. We did not investigate the frequency of this occurrence, and the ecological significance of these observations remains unclear. However, with the ever-increasing number of sea-cages used for global aquaculture, this is clearly a topic for further research.

Recent Growth, Biochemical Composition and Prey Field of Larval Haddock (Melanogrammus aeglefinus) and Atlantic Cod (Gadus morhua) on Georges Bank

1987 ◽  
Vol 44 (1) ◽  
pp. 14-25 ◽  
Author(s):  
L. J. Buckley ◽  
R. G. Lough
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Dry Weight ◽  
Melanogrammus Aeglefinus ◽  
Good Growth ◽  
Georges Bank ◽  
Larval Population ◽  
Prey Biomass ◽  
Recent Growth ◽  
Haddock Melanogrammus Aeglefinus

A transect across southern Georges Bank in May 1983 showed higher levels of available prey for haddock (Melanogrammus aeglefinus) and cod (Gadus morhua) larvae at two stratified sites than at a well-mixed site. At the stratified sites, prey biomass was high (30–300 μg dry wt∙L−1) near the surface above the thermocline; values were lower and more uniform with depth (10–30 μg dry wt∙L−1) at the well-mixed site. Larval population centers generally coincided with prey biomass vertically. Recent growth in dry weight of haddock larvae as estimated by RNA–DNA ratio analysis was higher at the stratified sites (8–13%∙d−1) than at the well-mixed site (7%∙d−1). Larvae appeared to be in excellent condition at the stratified sites, but up to 50% of haddock larvae from the well-mixed site had RNA–DNA ratios in the range observed for starved larvae in the laboratory. Cod collected at the same site were in better condition and growing faster than haddock. The data support the hypotheses that (1) stratified conditions in the spring favor good growth and survival of haddock larvae and (2) cod larvae are better adapted to grow and survive in well-mixed waters at lower levels of available food than haddock larvae.

scholarly journals Taxonomy of the Empria hungarica species-group (Hymenoptera, Tenthredinidae) in Northern Europe

1999 ◽  
Vol 10 (2) ◽  
pp. 95-101 ◽  
Author(s):  
Mikk Heidemaa ◽  
Matti Viitasaari
Keyword(s):  
Species Group ◽  
Northern Europe ◽  
European Species ◽  
Diagnostic Characters ◽  
Northern European ◽  
First Time

In the tenthredinid hymenopteran genus Empria, the European species with a paired whitish patch on tergum 1 are considered tentatively as a species-group termed the E. hungarica group. The type materials of Empria pumila (Konow), E. pumiloides Lindqvist and E. tricornis Lindqvist were examined. The lectotype and paralectotypes of E. pumila are designated, and new diagnostic characters for E. pumila and E. pumiloides are given. A key for the Northern European species of the E. hungarica group is compiled. The results of a comparison of the phenology and some metrical characters of the adults of E. pumila and E. pumiloides are presented in the form of diagrams. E. pumiloides is recorded for the first time from Russia and Germany. The records of E. hungarica from Estonia (Saaremaa) are reported as the northernmost for that species. All available distributional records of Empria hungarica in the Palaearctic are given in the text, and those localized reliably are also mapped.

Distinguishing Between One-Day-Old Cod (Gadus morhua) and Haddock (Melanogrammus aeglefinus) Eggs by Gas Chromatography and SIMCA Pattern Recognition

1985 ◽  
Vol 42 (11) ◽  
pp. 1823-1826 ◽  
Author(s):  
H. Knutsen ◽  
E. Moksnes ◽  
N. B. Vogt
Keyword(s):  
Fatty Acids ◽  
Pattern Recognition ◽  
Gas Chromatography ◽  
Multivariate Analysis ◽  
Methyl Ester ◽  
Gadus Morhua ◽  
Melanogrammus Aeglefinus ◽  
One Step ◽  
High Resolution Gas Chromatography ◽  
Haddock Melanogrammus Aeglefinus

Single cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) eggs were acid hydrolized. All the fatty acids were liberated and converted to methyl ester in a one-step reaction. The nonpolar hexane extract was analyzed by high resolution gas chromatography (HRGC). Selected peaks, occurring in both types of samples and in all chromatograms, were used to create a matrix for multivariate analysis. We conclude that cod and haddock eggs can be distinguished using this method.

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