scholarly journals length at first maturity of two species of lantern sharks (etmopterus spinax and etmopterus pusillus) off southern portugal

2005 ◽  
Vol 85 (5) ◽  
pp. 1163-1165 ◽  
Author(s):  
rui coelho ◽  
karim erzini
Keyword(s):  
Deep Water ◽  
Shark Species ◽  
Fishing Mortality ◽  
Portuguese Coast ◽  
Southern Portugal ◽  
First Maturity ◽  
Late Maturation ◽  
Size At First Maturity

etmopterus spinax and etmopterus pusillus are captured in large quantities in some deep-water fisheries along the portuguese coast and are always discarded. specimens were collected from february 2003 to may 2004 from deep-water fisheries and classified as mature or immature. maturity ogives were fitted and size at first maturity estimated for each sex of each species. both species are late maturing, with the maturity sizes varying between 75% and 87% of the maximum observed sizes, depending on species and sex. for both species, females tended to mature at and grow to larger sizes than males. the late maturation of these deep-water shark species makes these populations extremely vulnerable to increasing fishing mortality.

scholarly journals Filling biological information gaps of the marine topshell Phorcus sauciatus (Gastropoda: Trochidae) to ensure its sustainable exploitation

2018 ◽  
Vol 99 (4) ◽  
pp. 841-849 ◽  
Author(s):  
Ricardo Sousa ◽  
Joana Vasconcelos ◽  
João Delgado ◽  
Rodrigo Riera ◽  
José A. González ◽  
...  
Keyword(s):  
Biological Information ◽  
Fishing Mortality ◽  
Age Classes ◽  
Recruitment Pattern ◽  
Hydric Stress ◽  
First Maturity ◽  
Yield Per Recruit ◽  
Closed Season ◽  
Size At First Maturity

AbstractTopshells play a pivotal role in intertidal rocky ecosystems and are adapted to harsh thermal and hydric stress. Phorcus sauciatus, a common grazer in the Macaronesian region (Madeira and the Canaries), has rarely been studied due to its restricted geographic distribution compared with Phorcus lineatus. Monthly samples were taken throughout 2017 to analyse biological parameters and evaluate the harvesting effect on the stocks of this species in Madeira. Individuals of the first age classes (<4 years) were dominant (~89%), while immature individuals were more abundant during the summer season. The spawning season occurs between March and August, especially from March to June. The size at first maturity was 12.95 mm long (1.68 years), with a continuous recruitment pattern throughout the year. Yield-per-recruit analysis (Y/R) showed that maximum production is achieved at a fishing mortality of 1.7 year−1, corresponding to a Y/R of 0.023 g. Currently, Phorcus sauciatus seems to be moderately exploited in Madeira, but urgent conservation measures, such as a landing obligation, the establishment of a minimum catch size of 15 mm length, and a closed season (February–May), are warranted to preserve stocks of this species in the medium to long term.

Relative growth and size at first maturity of the deep water shrimp,Heterocarpus Ensifer (Decapoda, Pandalidae) from the southern Gulf of Mexico

Crustaceana ◽  
2007 ◽  
Vol 80 (5) ◽  
pp. 555-568 ◽  
Author(s):  
Enrique Lozano-Álvarez ◽  
Ana Vázquez-Bader ◽  
Patricia Briones-Fourzán ◽  
Adolfo Gracia
Keyword(s):  
Gulf Of Mexico ◽  
Deep Water ◽  
Relative Growth ◽  
Southern Gulf Of Mexico ◽  
First Maturity ◽  
Size At First Maturity

Biological aspects of deep-water sharks Centroscymnus coelolepis and Centrophorus squamosus in Galician waters (north-western Spain)

2006 ◽  
Vol 86 (4) ◽  
pp. 843-846 ◽  
Author(s):  
R. Bañón ◽  
C. Piñeiro ◽  
M. Casas
Keyword(s):  
Deep Water ◽  
Length Distribution ◽  
Shark Species ◽  
Bathymetric Range ◽  
North East ◽  
Biological Aspects ◽  
Western Spain ◽  
First Maturity ◽  
North Western ◽  
Size At Birth

Biological observations on two deep-water shark species, Portuguese dogfish Centroscymnus coelolepis and leafscale gulper shark Centrophorus squamosus, were made for specimens caught by bottom trawl and longline between 500 and 1300 m depth off the continental slope of Galicia and Galician Bank (north-east Atlantic) in the years 1996–1998. This includes data on their bathymetric range, length distribution, size at first maturity, ovarian fecundity, uterine fecundity and the size at birth.

scholarly journals Fecundity, histomorphology of the ovary and size at first maturity of Neolissochilus hexagonolepis (McClelland) in Tamor River, Nepal

2020 ◽  
Vol 12 (3) ◽  
pp. 401-410
Author(s):  
Suren Subba ◽  
Vinod Kumar Mahaseth ◽  
Bharat Raj Subba ◽  
Shyam Narayan Labh
Keyword(s):  
Fishery Management ◽  
Fork Length ◽  
Reproductive Traits ◽  
Breeding Period ◽  
Absolute Fecundity ◽  
Fish Samples ◽  
Measuring Tape ◽  
The Mean ◽  
First Maturity ◽  
Size At First Maturity

Neolissochilus hexagonolepis (McClelland, 1839) is one among the notable species in snow-fed torrential rivers of Nepal. The present study attempts to investigate some reproductive traits of N. hexagonolepis, including the length at first maturity, fecundity and its relationships with biometric variables like lengths (TL, SL, and FL) and weights (TW and OW) of the fish in the mid-reaches of Tamor River, Nepal. A total of 109 fish samples were collected from the river. For each individual, total length (TL), standard length (SL) and fork length (FL) were measured in a fully stretched condition to the nearest 1mm using a measuring tape and graduated ruler, while total weight (TW) and ovary weight (OW) was measured using a digital balance with the precision of 0.01 g. The mean absolute fecundity (F) was 8356.44 ± 4612.59 and ranged from 2398.6 to 20160. SL was more significantly correlated with absolute fecundity (R2=0.59; p<0.001) than other body metrics. The results showed that female individuals of N. hexagonolepis attained the first sexual maturity at TL 32.9 cm. N. hexagonolepis exhibited a protracted breeding period with its ovaries passing through six different stages of maturation. The finding of the present study may serve as a protocol for fishery biologists and managers to promulgate adequate regulations for continual fishery management in the River Tamor, Nepal.

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