Absolute Fecundity (absolute + fecundity)

Distribution by Scientific Domains

Selected Abstracts

Reproduction biology of pikeperch (Sander lucioperca (L.)) , a review

J. Lappalainen
Abstract,,, The present review focuses on the reproduction biology of pikeperch (Sander lucioperca (L.)). Aspects like maturity, fecundity, spawning migrations, spawning habitats, onset of spawning, and development time of eggs were reviewed. The onset of maturity is reached at younger age in southern than northern populations due to higher growth rate in the south. Males mature at smaller size and are on average younger than females. Absolute fecundity is closely related to the length and weight, but no clear relationship could be found between relative fecundity and length. Statistically significant relationships were found between the onset of spawning and latitude, and between the duration of the development time of eggs and stable water temperature. Near the southern limits of distribution, the onset of spawning is in February while near the northern limits it is in June. The interannual variability in fecundity and in the onset of maturity and further the factors affecting them have not been studied much. Furthermore, it is not known whether these variations could affect the population dynamics of pikeperch. Little is also known about the actual spawning behaviour of pikeperch in natural habitats. This is probably due to the typical spawning habitats located at 1,3 m depth in waters with high turbidity and low visibility. Even though the homing behaviour to the same spawning areas is well developed in adults, it is not known whether the adults were actually born in the same area. [source]

Life history characteristics of an invasive cyprinid fish (Carassius gibelio) in Chimaditis Lake (northern Greece)

I. D. Leonardos
Summary The life history characteristics of an invasive cyprinid fish, the Prussian carp (Carassius gibelio) were examined in Lake Chimaditis (northern Greece). The population is dominated by females that are able to reproduce gynogenetically. Fish samples were collected using trammel nets from August 2004 to July 2005. Their total length (TL) ranged between 21.9 and 37.0 cm. The length,weight relationship was W = 0.0336TL2.81 (r2 = 0.92, n = 600) and the mean Fulton condition factor exhibited monthly variation from 0.172 (May) to 0.186 (August). According to the annual growth marks present, the lifespan of the Prussian carp in Lake Chimaditis is 6 years. The growth parameters were estimated as L, = 34.46 cm, K = 0.297 year,1, t0 = ,1.994 year. Absolute fecundity (FA) ranged between 26 000 and 176 600 oocytes (mean = 66990) and relative fecundity between 78 and 251 oocytes per gram of total weight (mean = 158). Absolute fecundity increased exponentially with length (FA = 0.286 TL3.66, r2 = 0.66) and weight (FA = 17.93 W1.36, r2 = 0.73) of the fish. [source]

Reproductive features of the non-native Siganus luridus (Teleostei, Siganidae) during early colonization at Linosa Island (Sicily Strait, Mediterranean Sea)

E. Azzurro
Summary In July 2003, the finding of a newly settled population of Siganus luridus at Linosa Island (Sicily Strait, Mediterranean Sea) gave us the unusual opportunity to examine the reproductive condition of a Lessepsian migrant during early phases of colonization. Aspects of gonad morphology, fecundity, atresia and oocyte dynamics were investigated by using 43 pioneer specimens collected in concomitance with their first record in the Pelagie Islands. Ovarian development was consistent with the group-synchronous type, and testicular organization was of the unrestricted spermatogonial testis type, with cystic spermatogenesis. Both males and females had reached final stages of gonad maturation. The rates of follicular atresia were moderate: out of 17 adult females, 10 individuals did not present atretic oocytes; six exhibited <15.1% of secondary growth phase (SGP) oocytes in , -atresia, while one female presented 45.7% of SGP in , -atresia. Fecundity estimates did not diverge from what was observed in a reference population along the Lebanese coast. Absolute fecundity ranged from 115 739 to 740 433 oocytes per female (16.5,24.5 cm LT). Relative fecundity ranged from 1239 to 3162 oocytes g,1, with a mean of 1885 868 oocytes g,1. Our observations indicated that these early settled siganids are reproductively active at Linosa and suggested the forthcoming of self-maintaining populations across the central Mediterranean area. [source]

The biology of the bigeye grenadier at South Georgia

S. A. Morley
The biology of the bigeye grenadier Macrourus holotrachys caught as by-catch in the Patagonian toothfish Dissostichus eleginoides longline fishery conducted around South Georgia was investigated to improve data available for fisheries management. Age estimates suggest that M. holotrachys is a moderately slow growing species (K = 010), reaching ages of >30 years and attaining total lengths (LT) >80 cm (L, = 33). The size at which 50% of females had started to mature (Lint50) for M. holotrachys was 21 cm pre-anal length (LPA) and occurred at c. 9 years old. Estimates of natural mortality and Pauly's growth performance index were found to be low (M = 009 and , = 282 respectively). Gonad maturity stage was described from macroscopic and histological investigation. Mature ovaries had oocytes at all developmental stages with between 22 and 55% likely to be spawned each year. Absolute fecundity ranged from 22 000 to 260 000 eggs and was positively correlated with both pre-anal length and mass. A highly skewed sex ratio of 32 : 1, females : males, was found for specimens caught by longlines but not for a small sample of shallower trawl-caught specimens. It is suggested that females are far more susceptible to longline capture than males. Macrourus holotrachys is a bentho-pelagic predator and scavenger that feeds on a wide range of fishes and invertebrates. The fish are long lived, slow-growing species typical of deep-water grenadiers; fisheries management strategies should reflect their probable susceptibility to overfishing. [source]

Seasonal reproductive cycle of pike, Esox lucius L., from the River Danube

M. Lenhardt
Seasonal changes in ovaries and testes of the pike, sampled in the Danube (at 1163 and 1175 km) were analysed in this research. According to the presence of developing and resting oocytes in histological sections of pike ovaries sampled during August, it is possible to determine which female will be sexually mature the following spring. Active vitellogenesis starts in September (with oocyte diameters of 514 54 ,m and 453 68 ,m, at the upstream and downstream locality, respectively), at which time the differences between the developing and resting oocytes are even more obvious. Active spermatogenesis starts in September and lasts for 2 months, and by November primarily spermatozoa can be seen in histological sections. The reproductive score points to differences in samples from the two localities that can be explained by the differing characteristics of the habitat. Values of absolute fecundity (AF) ranged from 524 to 123 896 eggs, and the mean value of relative fecundity (RF) was 40.4 12.5. [source]

Effects of dietary highly unsaturated fatty acids and astaxanthin on the fecundity and lipid content of pond-reared Penaeus monodon (Fabricius) broodstock

Jian-Hua Huang
Abstract Five diets that contained fresh squid meat as the basic constituent and were supplemented with different amounts of highly unsaturated fatty acids (HUFA) and astaxanthin were fed to pond-reared Penaeus monodon broodstock. Diet A was sole squid meat. Diets B and C were supplemented with astaxanthin 50 and 100 mg kg,1 respectively. Diets D and E were supplemented with HUFA 5 and 10 g kg,1 and astaxanthin 50 mg kg,1 respectively. The result showed that the group fed diet E had the best reproductive performance in all experimental groups. It had a higher proportion of spawns (71.5%), spawning rate (0.047), a shorter latency period (7.70.3 d), higher absolute fecundity ( 103) (361.65.5) and egg production/female ( 103) (597.018.0) than all the other experimental groups. The fatty acid composition in broodstock diets strongly affected the tissue and fecundity of broodstock. Good correlations between the content of 20:4n-6 in eggs and the fecundity (r2=0.6109) and egg production (r2=0.9876) of broodstock were found. On the other hand, 22:6n-3 and DHA/EPA ratio was negatively correlated with the fecundity of broodstock (r2=0.5362, 0.8702 respectively). The result also showed that the balance between n-3 and n-6 fatty acid families, total polyunsaturated fatty acids and total saturated fatty acid and 20:5n-3 (EPA) and 22:6n-3 (DHA) may play vital roles in maturation and reproductive performance of P. monodon broodstock. [source]

Reproductive biology of pink dentex Dentex gibbosus (Rafinesque) from the Adriatic Sea, Croatia

Leon Grubisic
Abstract A 4-year study (May 1997,December 2000) of the reproductive biology of pink dentex Dentex gibbosus (Rafinesque) from the Adriatic Sea revealed that this species is a rudimentary hermaphrodite. The smallest mature males and females captured were 38.70 cm in total length (TL) and 39.80 cm in total length (TL) respectively. The von Bertalanffy growth parameters estimated for the entire population were: L,=107.24, K=0.12 and t0=,0.90. Fifty per cent of the population were sexually mature at 41.50 cm TL, while 100% of the specimens were sexually mature at 57.00 cm TL. Both monthly gonadosomatic index and macroscopically determined gonad stages strongly indicate that the pink dentex from the Adriatic Sea spawn partially in August, September and October. The mean value of absolute fecundity (F) was 1672 106 eggs. The results of great fertility of the pink dentex, partial spawning and relatively late sexual maturation suggest that the pink dentex has a high potential for commercial culture. [source]