scholarly journals Northern cod species face spawning habitat losses if global warming exceeds 1.5°C

2018 ◽  
Vol 4 (11) ◽  
pp. eaas8821 ◽  
Author(s):  
Flemming T. Dahlke ◽  
Martin Butzin ◽  
Jasmine Nahrgang ◽  
Velmurugu Puvanendran ◽  
Atle Mortensen ◽  
...  
Keyword(s):  
Habitat Suitability ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Climate Impacts ◽  
Polar Cod ◽  
Spawning Habitat ◽  
Spawning Areas ◽  
Climate Simulations ◽  
Northern Cod ◽  
Rcp 8.5

Rapid climate change in the Northeast Atlantic and Arctic poses a threat to some of the world’s largest fish populations. Impacts of warming and acidification may become accessible through mechanism-based risk assessments and projections of future habitat suitability. We show that ocean acidification causes a narrowing of embryonic thermal ranges, which identifies the suitability of spawning habitats as a critical life-history bottleneck for two abundant cod species. Embryonic tolerance ranges linked to climate simulations reveal that ever-increasing CO2emissions [Representative Concentration Pathway (RCP) 8.5] will deteriorate suitability of present spawning habitat for both Atlantic cod (Gadus morhua) and Polar cod (Boreogadus saida) by 2100. Moderate warming (RCP4.5) may avert dangerous climate impacts on Atlantic cod but still leaves few spawning areas for the more vulnerable Polar cod, which also loses the benefits of an ice-covered ocean. Emissions following RCP2.6, however, support largely unchanged habitat suitability for both species, suggesting that risks are minimized if warming is held “below 2°C, if not 1.5°C,” as pledged by the Paris Agreement.

scholarly journals Local cod (Gadus morhua) revealed by egg surveys and population genetic analysis after longstanding depletion on the Swedish Skagerrak coast

2018 ◽  
Vol 76 (2) ◽  
pp. 418-429 ◽  
Author(s):  
Henrik Svedäng ◽  
Julia M I Barth ◽  
Anders Svenson ◽  
Patrik Jonsson ◽  
Sissel Jentoft ◽  
...  
Keyword(s):  
North Sea ◽  
West Coast ◽  
Population Genetic ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Early Stage ◽  
Population Genetic Analysis ◽  
Swedish West Coast ◽  
The North ◽  
Spawning Areas

Abstract Dramatic and persistent reductions in Atlantic cod (Gadus morhua) are common in many coastal areas. While offshore cod stocks still were abundant and productive, the Swedish west coast showed signs of diminishing adult cod abundance at the beginning of the 1980s, where the local cod component was considered to be extirpated. To survey the present cod spawning activity and stock composition, we initiated egg trawling over two consecutive years (203 hauls in total) in combination with population genetic analyses (425 individually genotyped eggs). Here, we provide evidence of cod spawning at the Swedish Skagerrak coast, suggesting recolonization or that local cod has recovered from a nearly depleted state. Early stage eggs were found inside fjords too far to have been transported by oceanic drift from offshore spawning areas. The cod eggs were genetically similar in early to late life-stages and cluster mainly with the local adult cod, indicating that eggs and adults belong to the same genetic unit. The cod eggs were genetically differentiated from adult North Sea cod, and, to a lesser degree, also from the Kattegat and Öresund cod, i.e. indicating a possible recovery of local coastal stock. The patterns of the genetic structure in the inshore areas are, however, difficult to fully disentangle, as Atlantic cod in the North Sea-Skagerrak area seem to be a mixture of co-existing forms: local cod completing their entire life cycle in fjords and sheltered areas, and oceanic populations showing homing behaviours. The egg abundances are considerably lower compared with what is found in similar studies along the Norwegian Skagerrak coast. Nevertheless, the discovery of locally spawning cod along the Swedish west coast—although at low biomasses—is an encouraging finding that highlights the needs for endurance in protective measures and of detailed surveys to secure intraspecific biodiversity and ecosystem services.

Survival of Northern Atlantic Cod (Gadus morhua) Eggs and Larvae when Exposed to Ice and Low Temperature

1992 ◽  
Vol 49 (12) ◽  
pp. 2588-2595 ◽  
Author(s):  
Paul F. Valerio ◽  
Sally V. Goddard ◽  
Ming H. Kao ◽  
Garth L. Fletcher
Keyword(s):  
Low Temperature ◽  
Newfoundland And Labrador ◽  
Direct Contact ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Ice Crystals ◽  
Freeze Resistance ◽  
Northern Cod ◽  
Northern Atlantic ◽  
Eggs And Larvae

Freeze resistance of eggs and larvae of Atlantic cod (Gadus morhua) from the northern cod stock was investigated to determine whether ice contact could affect survival during the spring spawning season off Newfoundland. Egg and larval homogenates did not appear to contain antifreeze proteins (mean freezing points −0.78 and −0.88 °C, respectively). However, cod eggs did not freeze at −1.8 °C in icy aerated seawater, could be undercooled to −4.0 °C in ice, and froze at temperatures between −4.1 and −1 7 °C; freeze resistance depended on the integrity of the chorion. Larvae withstood undercooling to −1.8 °C, provided they were not brought into direct contact with ice crystals, if directly touched with ice, larvae froze at −1.36 °C (feeding stage) or −1.34 °C (yolk-sac), approximately 0.5 °C lower than would be expected from the freezing temperatures of their body fluids. The nature of their external epithelium and delayed development of sensitive gill structures below 0 °C may contribute to larval freeze resistance. Cod eggs and larvae are found in spring off Newfoundland and Labrador, when sea temperatures can be as low as −1.8 °C and ice cover extensive. While cod eggs are remarkably freeze resistant, such environmental conditions may cause freezing mortalities in larval cod.

Indices of Total Stock Biomass in the "Northern" and Gulf of St. Lawrence Atlantic Cod (Gadus morhua) Stocks Derived from Time Series Analyses of Fixed Gear (Trap) Catches

1992 ◽  
Vol 49 (2) ◽  
pp. 202-209 ◽  
Author(s):  
G. A. Rose
Keyword(s):  
Time Series ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Moving Average ◽  
Stock Biomass ◽  
Northern Cod ◽  
Cross Correlations ◽  
Time Series Analyses ◽  
Trap Catches ◽  
Total Stock

The hypothesis that annual catches of fixed gear fisheries are cross-correlated with stock biomass at lags predictable on the basis of the relative ages of fish comprising the catch and biomass was verified for the trapnet fisheries of the northeastern Newfoundland "northern" (NAFO 2J3KL) and northern "Gulf" of St. Lawrence (NAFO 3Pn4RS) Atlantic cod (Gadus morhua) stocks. Time series indices of stock biomass were derived from these cross-correlations. For northern cod, the index was a 3-yr weighted and lagged moving average of catch. For the years 1972–81 (the first half of the available data) the trap index (Ti) was regressed on the stock biomass (Bi) determined by sequential population models (SPA) (Ti = 0.477Bi0.638, r = 0.99, P < 0.01). Biomass forecasts for 1982–90 derived from this function (inverted) were positively correlated with recent SPA-based estimates (r = 0.94, P < 0.02). For Gulf cod, the index was a 4-yr weighted and lagged moving average of catch. This index was regressed on SPA-determined biomass for the years 1974–81 (Ti = −3.19 + 0.0217Bi, r = 0.99; P < 0.01). Biomass forecasts for 1982–90 were positively correlated with (but lower than) SPA-based biomass estimates for the Gulf stock (r = 0.91, P < 0.05).

scholarly journals Otolith chemistry and redistributions of Northern cod: evidence of Smith Sound – Bonavista Corridor connectivity

2018 ◽  
Vol 75 (12) ◽  
pp. 2302-2312 ◽  
Author(s):  
Victoria Neville ◽  
George Rose ◽  
Sherrylynn Rowe ◽  
Robyn Jamieson ◽  
Glenn Piercey
Keyword(s):  
Oxygen Isotope ◽  
Gadus Morhua ◽  
Direct Evidence ◽  
Atlantic Cod ◽  
Otolith Chemistry ◽  
Stable Oxygen Isotope ◽  
Metapopulation Structure ◽  
Northern Cod ◽  
Stable Oxygen ◽  
Placentia Bay

Stable oxygen isotope assays of otoliths (δ18Ooto) from migrant Atlantic cod (Gadus morhua Linnaeus, 1758) that overwintered in Smith Sound, Newfoundland, during 1995–2006 differed from those of nonmigrating summer residents and cod from Placentia Bay and Halibut Channel but did not differ from those of cod from the adjacent offshore Bonavista Corridor in summer. All fish sampled were of the 1990 year class (founder of the Smith Sound aggregation) at ages 8–10 years. Hence, overwintering Smith Sound and summering Bonavista Corridor cod likely experienced similar temperatures and salinities in each year of life, representing different migration stages of an intermixed group. Moreover, predictions of δ18Ooto from near-bottom ocean temperatures and salinities differed between inshore and offshore sites and, in general, matched observed signatures of inshore and offshore cod. The Bonavista Corridor cod, however, were an exception, having δ18Ooto signatures suggestive of inshore exposure. Our findings provide direct evidence of metapopulation structure in the Northern cod and are consistent with offshore rebuilding having been spurred by dispersal of cod from inshore Smith Sound.

scholarly journals Is recovery of northern cod limited by poor feeding? The capelin hypothesis revisited

2014 ◽  
Vol 71 (4) ◽  
pp. 784-793 ◽  
Author(s):  
Darrell R. J. Mullowney ◽  
George A. Rose
Keyword(s):  
Newfoundland And Labrador ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Wild Fish ◽  
Fish Growth ◽  
Small Fish ◽  
Performance Trends ◽  
Northern Cod ◽  
Capelin Mallotus Villosus ◽  
Prime Condition

Abstract The slow recovery of the “northern” Atlantic cod (Gadus morhua) stock off Newfoundland and Labrador has been ascribed to many factors. One hypothesis is poor feeding and condition as a consequence of a decline in capelin (Mallotus villosus), their former main prey. We compared the growth and condition of cod from known inshore (Smith Sound) and offshore (Bonavista Corridor) centres of rebuilding in wild subjects versus captive subjects fed an unlimited diet of oily rich fish. Wild fish in these areas have had different diets and population performance trends since stock declines in the early 1990s. Captive cod from both areas grew at the same rates and achieved equivalent prime condition, while their wild counterparts differed, with smaller sizes, lower condition in small fish, and elevated mortality levels in the offshore centre. Environmental temperature conditions did not account for the differences in performance of wild fish. Our results suggest that fish growth and condition, and hence rebuilding in the formerly large offshore spawning components of the northern cod, have been limited by a lack of capelin in their diet. Furthermore, we suggest that these groups are unlikely to rebuild until a recovery in capelin occurs.

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

Antifreeze glycoproteins in the plasma of Newfoundland Atlantic cod (Gadus morhua)

1981 ◽  
Vol 59 (11) ◽  
pp. 2186-2192 ◽  
Author(s):  
Choy L. Hew ◽  
Don Slaughter ◽  
Garth L. Fletcher ◽  
Shashikant B. Joshi
Keyword(s):  
Amino Acid ◽  
High Performance ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Antifreeze Proteins ◽  
Gel Filtration ◽  
Exchange Chromatography ◽  
Polar Cod ◽  
Antifreeze Glycoproteins ◽  
Molecular Weights

The plasma of the Atlantic cod, Gadus morhua, contained antifreeze glycoproteins which were present only during the winter months. The antifreeze proteins were isolated, using gel filtration and ion exchange chromatography, and characterized by high performance liquid chromatography. The antifreeze proteins appeared to consist of at least seven components with molecular weights ranging from 2 500 to 33 000. Chemical analysis of the larger components showed a predominance of alanine, threonine, and galactosamine in a ratio of 2:1:1. The smaller peptides contained proline, in addition to alanine and threonine. The amino acid sequence of the smallest glycopeptide (molecular weight 2500) was found to be Ala Ala Thr Pro Ala Thr Ala Ala Thr Pro Ala Thr Ala Ala.These glycoproteins are very similar, if not identical, in amino acid and carbohydrate composition to those isolated from Antaractic nototheniids and several northern gadoids. The sequence of the smallest glycopeptide from the Atlantic cod is identical to that reported for the polar cod, Boreogadus saida.

scholarly journals Does redistribution or local growth underpin rebuilding of Canada’s Northern cod?

2018 ◽  
Vol 75 (6) ◽  
pp. 825-835 ◽  
Author(s):  
George A. Rose ◽  
Sherrylynn Rowe
Keyword(s):  
Gadus Morhua ◽  
Local Population ◽  
Latitudinal Gradients ◽  
Individual Growth ◽  
Late Winter ◽  
Local Growth ◽  
Multiple Spawning ◽  
Spawning Areas ◽  
Northern Cod ◽  
Acoustic Surveys

The stock structure of Canada’s Northern cod (Gadus morhua), the largest of many depleted groundfish stocks having multiple spawning areas, is rebuilding by redistribution and not solely by local population growth. In 2007–2008, late winter acoustic surveys suggested initial rebuilding in the southern-most part of the offshore range (Bonavista Corridor, NAFO Divisions 3KL), likely including fish dispersing from the inshore. Thereafter, acoustically determined biomass increases averaged 30% per annum (to near 240 000 t in 2014). In contrast, formerly dominant stock areas farther north retained few fish, mostly juveniles. In 2015, however, biomass in the northern stock range (NAFO Division 2J) reached 65 000 t and mid-north Notre Dame Channel (3K) reached 101 000 t, with Bonavista Corridor declining to 136 000 t. Biomass pooled over all surveyed regions totaled 302 000 t, consistent with sustained 30% growth. Latitudinal gradients in cod size, age distributions, and individual growth existed both historically and recently, but not in 2015. The evidence suggests that the rapid increases of depopulated northern groups resulted from redistribution from the south within a metapopulation.

Observations of Adult Atlantic Cod (Gadus morhua) Overwintering in Nearshore Waters of Trinity Bay, Newfoundland

1994 ◽  
Vol 51 (1) ◽  
pp. 142-150 ◽  
Author(s):  
J. S. Wroblewski ◽  
Wade L. Bailey ◽  
Kristine A. Howse
Keyword(s):  
Minimum Distance ◽  
Short Range ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Nearshore Zone ◽  
Island Region ◽  
Northern Cod ◽  
Near Shore ◽  
Surgical Implantation ◽  
Trinity Bay

In the Random Island region of Trinity Bay, Newfoundland, individual adult Atlantic cod (Gadus morhua) with surgically implanted sonic transmitters were repeatedly relocated during the winter of 1990–91. Cod remained near shore, where seawater temperatures were as low as −1.5 °C. These fish did not move in the fall to offshore continental shelf waters as do most northern cod, nor did they move into the deeper waters of Trinity Bay that were slightly warmer than those in the nearshore zone. Of 12 cod released with transmitters in the fall and early winter, two were caught by local inshore fishermen the following spring, providing evidence that adult cod that overwinter nearshore become available to the spring inshore fishery. Another three were caught within a year of release. One fish was hooked in Fortune Bay on the southern coast of Newfoundland, having traveled a minimum distance of 305 nautical miles. These results demonstrate that northern cod can survive the surgical implantation of transmitters for at least a year and that this method is a valid technique for studying the behavior of northern cod. The main limitation to our sonic tracking was the relatively short range of signal reception (<1 nautical mile).

Sign in / Sign up

Export Citation Format

Share Document