Fecundity, Atresia, and Egg Size of Captive Atlantic Cod (Gadus morhua) in Relation to Proximate Body Composition

1991 ◽  
Vol 48 (12) ◽  
pp. 2333-2343 ◽  
Author(s):  
O. S. Kjesbu ◽  
J. Klungsøyr ◽  
H. Kryvi ◽  
P. R. Witthames ◽  
M. Greer Walker
Keyword(s):  
Gadus Morhua ◽  
White Muscle ◽  
Atlantic Cod ◽  
Dry Weight ◽  
Oocyte Diameter ◽  
Potential Fecundity ◽  
Spawning Period ◽  
The Mean ◽  
Egg Diameter ◽  
High Condition

Captive Atlantic cod (Gadus morhua) were fed at four ration levels (starvation, maintenance, moderate, and excess) for periods of 6–9 mo prior to and during spawning. At the end of the experiment, water, protein, glycogen, and fat contents of the liver, white muscle, and ovary were estimated. The depletion of the white muscle and liver was related to oocyte maturation and in particular to the proportion of eggs spawned (PES). The influx of protein into the ovary, the mean hydrated egg diameter, and the egg dry weight all reached maximum values at 10% PES and subsequently declined. Mean vitellogenic oocyte diameter was small prior to spawning but rose to a maximum at PES = 10%. Cod with high condition factors produced more previtellogenic oocytes and used a larger fraction during vitellogenesis. Actual fecundity of specimens deprived of food during the spawning period was between 20 and 80% of the potential fecundity depending on the nutritional status of the fish. Intensity of atresia in moderate ration fish increased from 0% at PES = 0% to 33% at PES = 80%. Estimates of durations of α-atretic vitellogenic oocytes varied between 10 and 13 d at 8 °C assuming a spawning period of 50 d.

Enhancing the reproductive potential of local populations of coastal Atlantic cod (Gadus morhua)

2002 ◽  
Vol 59 (10) ◽  
pp. 1685-1695 ◽  
Author(s):  
J S Wroblewski ◽  
H W Hiscock
Keyword(s):  
Gadus Morhua ◽  
Egg Quality ◽  
Atlantic Cod ◽  
Local Population ◽  
Reproductive Potential ◽  
Pseudopleuronectes Americanus ◽  
Farmed Fish ◽  
Potential Fecundity ◽  
Spawning Period ◽  
Natural Diet

We investigate the feasibility of enhancing the reproductive potential of northern Atlantic cod (Gadus morhua L.) populations resident in Newfoundland and Labrador bays by "catch, grow out, and release". This entails trapping juvenile and young adult fish from the local population, increasing their growth, maturation rate, and potential fecundity by feeding them a natural diet in net pens, and then returning the fish to their natal bay habitat to spawn. To determine whether multiyear farming affects spawning success, we determined the spawning period and egg quality of cod held in captivity for three growth seasons. Farmed cod spawned in a net pen concurrently with wild cod in Trinity Bay during 1995 and produced fertilized eggs from which viable larvae hatched. Sonic tracking showed that cod farmed for 3 years and then released reintegrated with wild cod aggregations over known spawning grounds. Recaptures of tagged fish several years after release suggest that farmed fish remained in the bay as members of the resident population. Fishing mortality (bycatch in coastal fisheries for lumpfish (Cyclopterus lumpus) and winter flounder (Pseudopleuronectes americanus)) of released farmed cod was not negligible, emphasizing that any enhancement effort must be carried out under a complete fishing moratorium.

Spawning behaviour of Atlantic cod, Gadus morhua: evidence of mate competition and mate choice in a broadcast spawner

1999 ◽  
Vol 56 (1) ◽  
pp. 97-104 ◽  
Author(s):  
Jeffrey A Hutchings ◽  
Todd D Bishop ◽  
Carolyn R McGregor-Shaw
Keyword(s):  
Mate Choice ◽  
Gadus Morhua ◽  
Dna Analysis ◽  
Atlantic Cod ◽  
Multiple Paternity ◽  
Reproductive Behaviour ◽  
Male Dominance ◽  
Male Body ◽  
Experimental Conditions ◽  
Spawning Period

We quantified individual differences in Atlantic cod, Gadus morhua, reproductive behaviour at a field-reported spawning density under experimental conditions. Marked individuals (nine females, seven males) were observed twice daily and videotaped continuously for 9 weeks at ambient photoperiod and temperature in a large tank (60 m3). Agonistic interactions appeared to maintain a size-based dominance hierarchy among males. Multiple paternity per spawning bout, revealed by microsatellite DNA analysis, suggested a link between dominance and fertilization success. Interactions between sexes were dominated by the circling of females by males. Predicated by vertical separation from males, and after descending to the bottom, a motionless female would be circled up to 17 times, often by one male per circling bout but by several males throughout the spawning period. Although circling frequency increased with male dominance and male body size, initiation and termination of this behaviour appeared to be under female control. Circling provides opportunities for males to gain individual access to reproductive females and for females to assess the quality of potential mates. Our evidence for nonrandom mate choice and for male-male competition and display has implications for Atlantic cod mating systems and effects of fishing on their reproductive success.

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.

Relationships Between RNA–DNA Ratio, Prey Density, and Growth Rate in Atlantic Cod (Gadus morhua) Larvae

1979 ◽  
Vol 36 (12) ◽  
pp. 1497-1502 ◽  
Author(s):  
L. J. Buckley
Keyword(s):  
Growth Rate ◽  
Nutritional Status ◽  
Growth Rates ◽  
Prey Density ◽  
Gadus Morhua ◽  
Slow Growth ◽  
Atlantic Cod ◽  
Larval Fish ◽  
Dry Weight ◽  
Dna And Rna

The protein, DNA, and RNA content of larvae maintained at 1.0 plankter/mL increased at the rates of 9.3, 9.9, and 9.8% per day, respectively, for the 5 wk after hatching. Protein reserves of larvae held at 0 or 0.2 plankters/mL were depleted by 45 and 35%, respectively, prior to death 12–13 d after hatching. Starved larvae had similar protein concentrations (percent of dry weight), lower RNA concentrations, and higher DNA concentrations than fed larvae. Larvae held at higher plankton densities had higher RNA–DNA ratios and faster growth rates than larvae held at lower plankton densities. The RNA–DNA ratio was significantly correlated (P < 0.01) with the protein growth rate. The RNA–DNA ratio appears to be a useful index of nutritional status in larval Atlantic cod (Gadus morhua) and may be useful for determining if cod larvae were in a period of rapid or slow growth at the time of capture. Key words: RNA–DNA ratio, starvation, protein, nucleic acids, growth, larval fish, Atlantic cod

scholarly journals Genetic characteristics of broodstock collected from four Norwegian coastal cod (Gadus morhua) populations

2006 ◽  
Vol 63 (2) ◽  
pp. 209-215 ◽  
Author(s):  
G. Dahle ◽  
K.E. Jørstad ◽  
H.E. Rusaas ◽  
H. Otterå
Keyword(s):  
Gadus Morhua ◽  
White Muscle ◽  
Atlantic Cod ◽  
Genetic Differences ◽  
Offspring Performance ◽  
Genetic Characteristics ◽  
Aquaculture Industry ◽  
Initial Selection ◽  
Selection Of ◽  
Spawning Sites

Abstract The aquaculture industry in Norway is now focused on developing economically viable farming based on the Atlantic cod, Gadus morhua. Extensive research has been carried out on this species for the past two decades, much of it in connection with stock enhancement. Until now, most of the intensive cage culture has been based on wild broodstock. However, a future cod aquaculture industry must be based on a domesticated broodstock, and the initial selection of wild cod becomes an important issue. Genetic differentiation between coastal cod populations in Norway has been reported, and it is of interest to evaluate offspring from some of these populations under farmed conditions. Live mature cod were collected at four selected spawning sites along the Norwegian coast (Porsangerfjord, Tysfjord, Herøy/Helgeland, and Øygarden). The fish were transported to Parisvatnet, a cod aquaculture facility west of Bergen, where they were kept in net pens. Individual tagging and extensive sampling (blood, white muscle, and fin clips) for genetic characterization were carried out. Each potential broodstock fish was genotyped at the haemoglobin and pantophysin I loci in addition to five allozyme (LDH-3∗, GPD∗, IDH-2∗, PGM∗, PGI-1∗) and ten microsatellite loci (Gmo2, Gmo3, Gmo8, Gmo19, Gmo34, Gmo35, Gmo36, Gmo37, Gmo132, Tch11). Comparison of allele frequencies revealed significant genetic differences among some of the coastal cod samples, and offspring performance of the broodstock is now being compared under farmed conditions. The overall test revealed significant genetic differences among the coastal broodstocks, with the HbI, PanI and the microsatellite Gmo132 loci being most informative.

An individual-based analysis of the variability of eggs and their newly hatched larvae of Atlantic cod (Gadus morhua) on the Scotian Shelf

1995 ◽  
Vol 52 (5) ◽  
pp. 1083-1093 ◽  
Author(s):  
Thomas J. Miller ◽  
Tomasz Herra ◽  
William C. Leggett
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Seasonal Pattern ◽  
Size Variation ◽  
Seasonal Temperature ◽  
Scotian Shelf ◽  
Larval Size ◽  
Newly Hatched Larvae ◽  
Shelf Region ◽  
Egg Diameter

We assessed the seasonal pattern of size variation in cod eggs on the Scotian Shelf region of the Northwest Atlantic during the period March 1991–May 1993. Cod eggs were present from October to May during the surveys. Spawning was not strongly bimodal. There was a dominant autumn peak, in contrast to the historically dominant spring spawning. Egg diameter varied seasonally. Seasonal temperature patterns explained 52% of the variation in egg diameter. By incubating the eggs on-board ship, we also assessed the seasonality of the standard length (SL) of larvae that hatched from these eggs. Larval SL also varied seasonally. Egg diameter and SL were significantly correlated, but the correlation was weak (r2 = 0.3). However, the strength of correlation was consistent with laboratory estimates based on individual data. The results suggest that previous estimates of the egg size – larval size correlations are inflated. Temperature exerted a significant effect on both egg diameter and larval size, and is hypothesized to be the agent responsible for the observed seasonal variation.

Some ectoparasitic trichodinids from Atlantic cod, Gadus morhua L., with a description of Trichodina cooperi n.sp.

1989 ◽  
Vol 67 (7) ◽  
pp. 1793-1800 ◽  
Author(s):  
S. L. Poynton ◽  
J. Lom
Keyword(s):  
Nova Scotia ◽  
Body Surface ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Geographic Range ◽  
The Body ◽  
Wild Fish ◽  
Eastern Canada ◽  
Mean Diameter ◽  
The Mean

Trichodina murmanica Polyanskiy, 1955 (= Trichodina domerguei subsp. saintjohnsi Lom and Laird, 1969) and Trichodina cooperi n.sp. were commonly encountered on skin and fins of Atlantic cod, Gadus morhua L., near Halifax, Nova Scotia, Canada. A third species of Trichodina, probably new, was recorded from the skin of one fish. This is believed to be the first report of the genus Trichodina from the body surface of gadoid fish from eastern Canada, and the known geographic range of T. murmanica is extended. Trichodina cooperi n.sp. has an adoral ciliary spiral of 370–380° and is relatively large, the mean diameter of the body is 110 μm, of the adhesive disc (with dark center), 95 μm, and of the denticulate ring, 59 μm. The denticulate ring consists of 24–29 denticles (usually 27), with 7–9 radial pins per denticle. Each denticle has a broad blade, a large central part, and a slightly curved thorn of moderate to broad width, with a central rib when mature. The thorn is approximately twice the length of the blade. The horseshoe-shaped macronucleus has a diameter of 80.0 μm and the micronucleus is in the +y position. Trichodina spp. infected 26% of 39 wild fish 20 to < 60 cm long. Most wild fish yielded less than five ciliates per 24 × 50 mm smear.

Dietary influence on quality of farmed Atlantic cod (Gadus morhua): Effect on glycolysis and buffering capacity in white muscle

Aquaculture ◽  
2006 ◽  
Vol 252 (2-4) ◽  
pp. 409-420 ◽  
Author(s):  
Oddhild Førde-Skjærvik ◽  
Olaf Skjærvik ◽  
Turid Mørkøre ◽  
Magny S. Thomassen ◽  
Kjell-Arne Rørvik
Keyword(s):  
Gadus Morhua ◽  
White Muscle ◽  
Atlantic Cod ◽  
Buffering Capacity

PACAP and nitric oxide inhibit contractions in the proximal intestine of the atlantic cod, Gadus morhua

2000 ◽  
Vol 203 (3) ◽  
pp. 575-583 ◽  
Author(s):  
C. Olsson ◽  
S. Holmgren
Keyword(s):  
Nitric Oxide ◽  
Smooth Muscle ◽  
Intestinal Motility ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Inhibitory Response ◽  
Nitric Oxide Donor ◽  
The Mean ◽  
Proximal Intestine ◽  
Spontaneous Contractions

The possible inhibitory roles of pituitary adenylate cyclase-activating polypeptide (PACAP), vasoactive intestinal polypeptide (VIP) and nitric oxide in the control of intestinal motility were investigated in the Atlantic cod, Gadus morhua. Circular and longitudinal smooth muscle preparations developed spontaneous contractions that were inhibited by atropine (10(−)(5)mol l(−)(1)). PACAP 27 and PACAP 38 (10(−)(7)mol l(−)(1)) reduced the amplitude of the contractions but did not usually affect the resting tension. In the circular preparations, the mean active force developed (above resting level; +/− s.e.m.) was reduced from 0. 62+/−0.18 mN to 0.03+/−0.03 mN (N=10) by PACAP 27 and from 0.53+/−0. 20 mN to 0.31+/−0.13 mN (N=7) by PACAP 38, while neither cod nor mammalian VIP (10(−)(10)-10(−)(6)mol l(−)(1)) had any effect. In the longitudinal preparations, PACAP 27 reduced the force developed from 1.58+/−0.22 mN to 0.44+/−0.25 mN (N=8) and PACAP 38 reduced it from 1.61+/−0.47 mN to 0.75+/−0.28 mN (N=5). The nitric oxide donor sodium nitroprusside (NaNP) almost abolished the contractions in the circular preparations, reducing the mean force developed from 0. 47+/−0.05 mN to 0.02+/−0.06 mN (10(−)(6)mol l(−)(1); N=9) and 0+/−0. 07 mN (10(−)(5)mol l(−)(1); N=8). In the longitudinal preparations, NaNP reduced the force developed from 2.03+/−0.36 mN to 0.33+/−0.22 mN (10(−)(6)mol l(−)(1); N=8) and 0.19+/−0.30 mN (10(−)(5)mol l(−)(1); N=8). The L-arginine analogue N(G)-nitro-L-arginine methyl ester (L-NAME; 3×10(−)(4)mol l(−)(1)) enhanced the contractions in both circular and longitudinal preparations, increasing the mean force developed from 0.51+/−0.12 mN to 0.94+/−0.21 mN (N=8) and from 1.49+/−0.36 mN to 3.34+/−0.67 mN (N=7), respectively. However, preincubation with L-NAME before a second addition of PACAP 27 (10(−)(7)mol l(−)(1)) did not affect the response to PACAP, neither did preincubation with the guanylate cyclase inhibitor 6-anilinoquinoline-5,8-quinone (LY83583; 10(−)(5)mol l(−)(1)), while the inhibitory response to NaNP (3×10(−)(7)mol l(−)(1)) was abolished by LY83583. The PACAP analogue PACAP 6–27 (3×10(−)(7)mol l(−)(1)) had no effect on the response to either NaNP (3×10(−)(7)mol l(−)(1)) or PACAP 27 (10(−)(8)mol l(−)(1)) in the circular preparations. These findings indicate the presence of both a cholinergic and a nitrergic tonus in the smooth muscle preparations of the cod. Although PACAP and NaNP both inhibit contractions, there is no evidence of any interactions between the two substances. In addition, NaNP, but not PACAP, probably acts via stimulating the production of cyclic GMP. In conclusion, both PACAP and nitric oxide may act as inhibitory transmitters, using distinct signalling pathways, in the control of intestinal motility in the Atlantic cod.

Sign in / Sign up

Export Citation Format

Share Document