Evidence for protandry in Polydactylus quadrifilis in the Kwanza Estuary, Angola, and its implications for local fisheries

Butler, Edward C; Childs, Amber-Robyn; Winkler, Alexander C; Milner, Marianne V; Potts, Warren M

Title: Evidence for protandry in Polydactylus quadrifilis in the Kwanza Estuary, Angola, and its implications for local fisheries
Creator: Butler, Edward C
Creator: Childs, Amber-Robyn
Creator: Winkler, Alexander C
Creator: Milner, Marianne V
Creator: Potts, Warren M
Date Issued: 2018
Date: 2018
Type: text
Type: article
Identifier: http://hdl.handle.net/10962/124451
Identifier: vital:35614
Identifier: https://doi.10.1007/s10641-017-0699-6
Description: A total of 141 Polydactylus quadrifilis were sampled from the Kwanza Estuary in Angola ranging in size from 436 to 1360 mm fork-length (FL). Of these, 124 were male, six intersex and 11 female. Female fish were significantly longer (mm, FL) and heavier (kg) than males and had significantly higher gonadosomatic indices (GSI’s) than those of males and intersex fish. Transitional (intersex) gonads were delimited, with testicular and ovarian regions separated by connective tissue. The first signs of ovarian tissue appeared on the outer ventral surface of the gonad. A second layer of ovarian tissue was first noticeable at either end of the initial ovarian region and developed back towards the centre of the ventral wall to form a luminal space. Early-stage oocytes were commonly found in the outer area of male regions and residual late-stage spermatids and spermatozoa were found in the luminal space of ovarian regions, suggesting a process of sex change from the outside inwards. A loss of male function was noted with increased ovarian prevalence. Based on this evidence it is suggested that P. quadrifilis in the Kwanza Estuary are protandrous. Owing to the reliance of P. quadrifilis on large highly fecund females for egg production, it is likely that they will be sensitive to fishing practices that target larger individuals within the population.
Format: 13 pages
Format: pdf
Language: English
Relation: Environmental Biology of Fishes
Relation: Butler, E.C., Childs, A.R., Winkler, A.C., Milner, M.V. and Potts, W.M., 2018. Evidence for protandry in Polydactylus quadrifilis in the Kwanza Estuary, Angola, and its implications for local fisheries. Environmental biology of fishes, 101(2), pp.301-313
Relation: Environmental Biology of Fishes volume 101 number 2 301 313 2018 0378-1909
Rights: Environmental Biology of Fishes
Rights: Use of this resource is governed by the terms and conditions of the SpringerLink Terms of Use Statement ( https://link.springer.com/termsandconditions))

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