scholarly journals Otoliths of Arctic Cod (Boreogadus saida), Small Atlantic Cod (Gadus morhua), and Three Other Fish Species from Newfoundland Waters: Description and Relationship of Body Length to Otolith Lengths

1994 ◽  
Vol 16 ◽  
pp. 33-40 ◽  
Author(s):  
W W Lidster ◽  
G R Lilly ◽  
E G Dawe
Keyword(s):  
Body Length ◽  
Fish Species ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Boreogadus Saida ◽  
Arctic Cod ◽  
Relationship Of

Accuracy and precision in stock separation of north-east Arctic and Norwegian coastal cod by otoliths - comparing readings, image analyses and a genetic method

2005 ◽  
Vol 56 (5) ◽  
pp. 753 ◽  
Author(s):  
Erik Berg ◽  
Tuula H. Sarvas ◽  
Alf Harbitz ◽  
Svein Erik Fevolden ◽  
Arnt Børre Salberg
Keyword(s):  
Visual Inspection ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Complete Separation ◽  
Arctic Cod ◽  
Genetic Method ◽  
North East ◽  
Accuracy And Precision ◽  
Growth Zones ◽  
The Difference

The distinction between north-east Arctic cod and Norwegian coastal cod, two major groups of Atlantic cod (Gadus morhua L.), has for many years been based on different distance and shape similarities between the two first translucent growth zones in the otoliths, subjectively decided by visual inspection in a binocular. To analyse the certainty of this technique, four independent readers have classified 263 cod otoliths in total from five different geographical areas. For three of the readers, between 82% and 89% of the classification results coincided with independent results based on genetic analyses. Further, 38 cod otoliths, where the readers were certain of the classification (21 north-east Arctic cod and 17 coastal cod) were classified by several image analysis methods. A complete separation was obtained by using the ratio of the circumferences of the two zones, providing a typical ratio of approximately 2 for coastal and 1.5 for north-east Arctic cod. The otolith method for separating the two types of cod has been considered adequately accurate in assessing the two stocks of cod. However, the method is sensitive to subjective interpretation, and action needs to be taken to minimise the difference in interpretation among otolith readers.

scholarly journals Fish aggregating sound technique (FAST): how low-frequency sound could be used in fishing and ranching of cod

2018 ◽  
Vol 75 (4) ◽  
pp. 1258-1268 ◽  
Author(s):  
Björn Björnsson
Keyword(s):  
Fish Species ◽  
Gadus Morhua ◽  
Greenhouse Gas Emission ◽  
Atlantic Cod ◽  
Benthic Communities ◽  
Low Frequency ◽  
Wild Fish ◽  
Sea Cage ◽  
Free Ranging ◽  
Harmful Effects

Abstract In marine fisheries, considerable development has occurred in capture technology. Yet, some of the current fishing methods impact the environment by large greenhouse gas emission, harmful effects to benthic communities, and/or high bycatch of juvenile and unwanted species. It is proposed that for some fish species these deficiencies could be mitigated by classical conditioning using sound and food reward to concentrate wild fish before capture with environmentally friendly fishing gear. Atlantic cod (Gadus morhua), which globally is among the fish species with the highest landed value, can be acoustically trained. In a sea cage, it takes about a week to train a group of naïve cod to associate low frequency (250 Hz) sound with food, whereas the training of a group of naïve cod accompanied with one trained cod takes less than a day. In inshore areas, it takes a few weeks to attract thousands of cod to stations where food is regularly delivered. These conditioned cod wait at the stations for their meals and do not mingle much with the unconditioned cod which hunt for wild prey. It is suggested that by calling acoustically conditioned fish between stations, a much larger number of naïve fish can be gathered. This so-called fish aggregating sound technique (FAST) may thus facilitate the accumulation of wild fish and expedite their capture with a purse seine or a trap in a way that minimizes fuel consumption and mortality of juveniles and unwanted species. The operation of FAST requires exclusive rights of a designated fishing area. The exclusivity makes it possible to on-grow the fish in free-ranging schools and sea cages for several months to increase their size and food quality before capture.

scholarly journals New encounters in Arctic waters: a comparison of metabolism and performance of polar cod (Boreogadus saida) and Atlantic cod (Gadus morhua) under ocean acidification and warming

Polar Biology ◽  
2016 ◽  
Vol 39 (6) ◽  
pp. 1137-1153 ◽  
Author(s):  
Kristina Lore Kunz ◽  
Stephan Frickenhaus ◽  
Silvia Hardenberg ◽  
Torild Johansen ◽  
Elettra Leo ◽  
...  
Keyword(s):  
Ocean Acidification ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Polar Cod ◽  
Boreogadus Saida ◽  
Polar Cod Boreogadus Saida ◽  
And Performance

scholarly journals Relationship of RNA/DNA ratio and temperature to growth in larvae of Atlantic cod Gadus morhua

2003 ◽  
Vol 262 ◽  
pp. 229-240 ◽  
Author(s):  
EM Caldarone ◽  
JM StOnge-Burns ◽  
LJ Buckley
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Relationship Of

Changes in the Diet of Demersal Fish due to Eutrophication-Induced Hypoxia in the Kattegat, Sweden

1994 ◽  
Vol 51 (2) ◽  
pp. 321-336 ◽  
Author(s):  
Leif Pihl
Keyword(s):  
Fish Species ◽  
Gadus Morhua ◽  
Prey Species ◽  
Atlantic Cod ◽  
Benthic Communities ◽  
Demersal Fish ◽  
Organic Enrichment ◽  
Fish Diet ◽  
Dietary Shift ◽  
Term Change

The diets of five dominant bottom-feeding fish species, Atlantic cod (Gadus morhua), whiting (Merlangius merlangus), plaice (Pleuronectes platessa), dab (Limanda limanda), and American plaice (Hippoglossoides platessoides), were analysed during spring and autumn between May 1984 and April 1988 in the southeast Kattegat. A general long-term change in the diet of bottom-feeding fish in the Kattegat has taken place since the beginning of the century and, for some of the species, the feeding pattern was different from that in adjacent areas. The observed dietary shift appeared to be due to changes in species composition of benthic macrofauna. Prey species favored by increased organic enrichment were dominant in the diet. Several infaunal species increased in dietary importance during recent hypoxia. In contrast, during hypoxia, a reduction of epibenthic crustaceans was observed in the fish diet. This study emphasizes the potential effects of organic enrichment and hypoxia (due to eutrophication) on trophic interactions in marine benthic communities. Repeated stress from hypoxia might favor small-sized prey species with a short life cycle, which would in turn favor small-sized fishes. Thus, altered food resources and the direct effects of hypoxia might result in shift in dominance among demersal fish species.

scholarly journals Animal Welfare Issues in Capture-Based Aquaculture

Animals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 956
Author(s):  
Uthpala Chandararathna ◽  
Martin Hugo Iversen ◽  
Kjetil Korsnes ◽  
Mette Sørensen ◽  
Ioannis N. Vatsos
Keyword(s):  
Fish Species ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Farming Systems ◽  
Recovery Phase ◽  
Market Size ◽  
Fish Welfare ◽  
Intensive Farming ◽  
Intensive Aquaculture ◽  
Aquaculture Production

Capture-based aquaculture (CBA) represents a type of intensive aquaculture production system for some economically valuable fish species, such as bluefin tuna (Thunnus thynnus), eel (Anguilla spp.) and Atlantic cod (Gadus morhua). In CBA, fish are captured from the wild in certain periods of the year, and following a recovery phase, they are kept in rearing facilities for a period of time, until they reach the market size. In this case, the fish are wild and have not gone through domestication like other fish species that are reproduced and farmed under the established farming systems. Therefore, these fish are not genetically adapted to live under the intensive farming conditions, and thus their welfare may be compromised in different manners compared to their domesticated counterparts. This review presents an overview of the current situation of CBA, while focusing on the assessment of fish welfare in CBA. The most commonly used fish welfare indicators will be discussed in relation to the different stages of CBA.

scholarly journals Low incidence of plastic ingestion among three fish species significant for human consumption on the island of Newfoundland, Canada

2019 ◽  
Author(s):  
Max Liboiron
Keyword(s):  
Atlantic Salmon ◽  
Fish Species ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Human Consumption ◽  
Cultural Importance ◽  
Capelin Mallotus Villosus ◽  
Food Fish ◽  
Low Incidence ◽  
Contamination Levels

This study reports the first baselines of plastic ingestion for three fish species that are common commercial and sustenance food fish in Newfoundland. Species collections occurred between 2015 and 2016 for Atlantic cod (Gadus morhua), Atlantic salmon (Salmo salar), and capelin (Mallotus villosus). The frequency of occurrence (%FO) of plastic ingestion for both Atlantic salmon (n = 69) and capelin (n = 350) was 0%. Of the 1010 Atlantic cod individuals collected over two years, 17 individuals had ingested plastics, a %FO of 1.68%. This is the only multi-year investigation of plastic ingestion in Atlantic cod for the Northwest Atlantic, and the first baseline of plastic ingestion in Atlantic salmon and capelin on the island of Newfoundland. Considering the ecological, economic, and cultural importance of these fish species, this study is the beginning of a longitudinal study of plastic ingestion to detect any future changes in contamination levels.

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