Diet and feeding niches of juvenile Gadus morhua, Melanogrammus aeglefinus and Merlangius merlangus during the settlement transition in the northern North Sea

2011 ◽  
Vol 79 (1) ◽  
pp. 89-111 ◽  
Author(s):  
D. K. Demain ◽  
A. Gallego ◽  
A. Jaworski ◽  
I. G. Priede ◽  
E. G. Jones
Keyword(s):  
North Sea ◽  
Gadus Morhua ◽  
Melanogrammus Aeglefinus ◽  
Merlangius Merlangus ◽  
Northern North Sea

scholarly journals Settlement length and temporal settlement patterns of juvenile cod (Gadus morhua), haddock (Melanogrammus aeglefinus), and whiting (Merlangius merlangus) in a northern North Sea coastal nursery area

2014 ◽  
Vol 71 (8) ◽  
pp. 2101-2113 ◽  
Author(s):  
Dorota K. Bastrikin ◽  
Alejandro Gallego ◽  
Colin P. Millar ◽  
Imants G. Priede ◽  
Emma G. Jones
Keyword(s):  
North Sea ◽  
Settlement Patterns ◽  
Gadus Morhua ◽  
Single Pulse ◽  
Demersal Fish ◽  
Population Connectivity ◽  
Nursery Area ◽  
Melanogrammus Aeglefinus ◽  
Inshore Waters ◽  
Northern North Sea

Abstract Knowledge of settlement timing and duration, which has been identified as an important milestone for demersal fish, is critical to understanding population connectivity, relevant to the development of spatially—and temporally—resolved conservation measures, and recruitment variability, as important density-dependent dynamics may take place at this stage. To study the settlement ecology of cod haddock, and whiting, sampling was conducted over spring and summer 2004–2006 at the northern North Sea nursery area. Over 4000 0-group juveniles were collected. Settlement was associated with clear and progressive changes in the prey composition of these juveniles. The size of fish that could be considered settled was estimated as 49 (±3) mm for cod, 78 (±4) mm for haddock, and 85 (±6) mm for whiting. Clear differences in temporal settlement patterns were also apparent. Cod settled in a single pulse lasting about a month (mid-May to mid-June) and initially occupied shallower, inshore waters, whereas haddock settled in one pulse, lasting ∼2 weeks (second half of May), favouring deeper, farther offshore locations. Whiting settled much later in the season and over a more protracted period (early June to early August), and their depth preferences also changed over time and with increasing length.

Discarding practices for commercial gadoids in the North Sea

1998 ◽  
Vol 55 (7) ◽  
pp. 1632-1644 ◽  
Author(s):  
Yorgos Stratoudakis ◽  
Robert J Fryer ◽  
Robin M Cook
Keyword(s):  
North Sea ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Melanogrammus Aeglefinus ◽  
The North ◽  
The North Sea ◽  
Merlangius Merlangus ◽  
Using Data ◽  
Species Specific ◽  
Catch Composition

Understanding fishers' discarding behaviour, and anticipating their reactions to changes in the biological or regulatory characteristics of a fishery, are important for dealing with the problem of discarding. In this paper, we investigate the discarding of haddock (Melanogrammus aeglefinus), whiting (Merlangius merlangus), and Atlantic cod (Gadus morhua) in the North Sea, using data collected by scientific observers onboard Scottish demersal vessels. We describe discarding on each trip by species-specific discard curves and explore how these curves depend on biological and regulatory variables. There are large differences in the size of discarded fish between inshore and offshore areas, with offshore-operating vessels discarding larger fish (high-grading). Increases in legal landing size correspond to immediate increases in the size of discarded fish, particularly for haddock and cod in inshore areas. In general, discarding practices for haddock and cod are similar over time and consistent across gears, whereas decisions for the lesser valued whiting are more variable and can be affected by the catch composition.

scholarly journals The vertical separation of fish in the aft end of a demersal trawl

2009 ◽  
Vol 66 (4) ◽  
pp. 772-777 ◽  
Author(s):  
Ludvig Ahm Krag ◽  
René Holst ◽  
Niels Madsen
Keyword(s):  
Vertical Distribution ◽  
Gadus Morhua ◽  
Melanogrammus Aeglefinus ◽  
Multinomial Model ◽  
Vertical Separation ◽  
Commercially Important ◽  
Merlangius Merlangus ◽  
The Vertical Distribution ◽  
Haddock Melanogrammus Aeglefinus ◽  
Important Fish

Abstract Krag, L. A., Holst, R., and Madsen, N. 2009. The vertical separation of fish in the aft end of a demersal trawl. – ICES Journal of Marine Science, 66: 772–777. Two multi-compartment separator frames were used to study the vertical separation of some commercially important fish species in the aft end of a trawl, with the aim of separating cod (Gadus morhua) from other species. A non-linear multinomial model with random effects was used to analyse the data and to compare the performance of the two frames. The vertical distribution of cod in the aft end of the trawl was close to uniform, whereas haddock (Melanogrammus aeglefinus), whiting (Merlangius merlangus), plaice (Pleuronectes platessa), and lemon sole (Microstomus kitt) showed more uneven distributions. The use of guiding bars in the separator frame significantly (p < 0.05) increased the catch of cod, plaice, and lemon sole in the upper compartment. The vertical separation of cod was density-dependent; high densities of fish resulted in a more uniform distribution of cod. The species separations found differ from those reported from the studies of species separation in the region of the trawl mouth.

Myxidium finnmarchicum n. sp. (Myxosporea: Myxidiidae) from the gall bladder of whiting Merlangius merlangus (L.) (Pisces: Teleostei) in North Norway

Zootaxa ◽  
2010 ◽  
Vol 2673 (1) ◽  
pp. 56 ◽  
Author(s):  
KEN MACKENZIE ◽  
CATHERINE COLLINS ◽  
CHAGANTI KALAVATI ◽  
WILLY HEMMINGSEN
Keyword(s):  
New Species ◽  
Gall Bladder ◽  
North Sea ◽  
Similar Species ◽  
The North ◽  
The Status ◽  
Merlangius Merlangus ◽  
Northern North Sea ◽  
A New Species ◽  
North Norway

A new species of myxosporean is described from the gall bladder of whiting Merlangius merlangus (L.) (Pisces: Teleostei) caught at the northernmost extremity of the range of this fish off the northwest coast of Finnmark county, North Norway. The new species, Myxidium finnmarchicum, is described morphologically and genetically and compared with other similar species of Myxidium reported from the gall bladders of gadid fish in the North Atlantic - M. sphaericum, M. gadi and M. bergense. Both the morphological and molecular descriptions support the status of Myxidium finnmarchicum as a new species. Myxidium sphaericum is a parasite of whiting in the North Sea, but the two species are separated geographically by an intervening area in the northern North Sea north of 58° N where no whiting has been found infected with any species of Myxidium. Based upon 18S rRNA analysis, M. finnmarchicum shows closest sequence identity to M. gadi. The confusion in the literature regarding the validity and host specificities of M. sphaericum, M. gadi, M. bergense and M. incurvatum is highlighted and discussed. We suggest that a more detailed investigation of the range of morphological and molecular variation in these parasites from their various reported host species is required.

scholarly journals Linking spawning ground extent to environmental factors — patterns and dispersal during the egg phase of four North Sea fishes

2018 ◽  
Vol 75 (3) ◽  
pp. 357-374 ◽  
Author(s):  
Hannes Höffle ◽  
Cindy J.G. Van Damme ◽  
Clive Fox ◽  
Stéphanie Lelièvre ◽  
Christophe Loots ◽  
...  
Keyword(s):  
North Sea ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Early Stage ◽  
Distribution Patterns ◽  
Melanogrammus Aeglefinus ◽  
Spawning Grounds ◽  
The North ◽  
Generalized Additive Mixed Models ◽  
Additive Mixed Models

Previous studies have shown that four commercially important demersal species, namely Atlantic cod (Gadus morhua), haddock (Melanogrammus aeglefinus), whiting (Merlangius merlangus), and European plaice (Pleuronectes platessa), spawn in distinct areas across the North Sea. Based on two comprehensive ichthyoplankton surveys in 2004 and 2009, the present study uses generalized additive mixed models to delimit these spawning grounds using the distribution of recently spawned eggs, investigates their relationship to specific environmental conditions, and examines egg dispersal during their development. Results indicate that presence–absence of early stage eggs is more related to temporal and topographic variables, while egg densities are closely linked with hydrography. Egg distribution patterns were relatively consistent during development and only changed near hatching. Compared with historic observations, the location of the spawning grounds appeared stable on the broad scale but centres of egg abundance varied between the surveyed years. Potential effects of long-term climate change and anthropogenic short-term disturbances, such as seismic surveys, on fish reproduction are discussed, pointing out the demand for multispecies studies on these issues.

Is Juvenile Natural Mortality in Marine Demersal Fish Variable?

1993 ◽  
Vol 50 (8) ◽  
pp. 1591-1598 ◽  
Author(s):  
Ransom A. Myers ◽  
Noel G. Cadigan
Keyword(s):  
Interannual Variability ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Demersal Fish ◽  
Independent Component ◽  
Melanogrammus Aeglefinus ◽  
Natural Mortality ◽  
Juvenile Mortality ◽  
Merlangius Merlangus ◽  
Haddock Melanogrammus Aeglefinus

We test the hypothesis that the interannual variability of the density-independent component of juvenile natural mortality is a major source of variability in abundance of marine demersal fish. Our tests use data on populations for which there are research surveys consisting of two simultaneous estimates of abundance of young juveniles soon after settlement and two more simultaneous estimates of the same cohort a year later. We applied our test to 14 populations of Atlantic cod (Gadus morhua), haddock (Melanogrammus aeglefinus), whiting (Merlangius merlangus), plaice (Pleuronectes platessa), and sole (Solea vulgaris). We conclude that, in all populations examined except North Sea sole, there was very little or no interannual variability in the density-independent component of juvenile mortality.

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