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Reproductive biology and environment...

Villoso, Enrico Palomera.

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Reproductive biology and environmental control of spawning cycle of weakfish, Cynoscion regalis (Bloch and Schneider), in Delaware Bay.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Reproductive biology and environmental control of spawning cycle of weakfish, Cynoscion regalis (Bloch and Schneider), in Delaware Bay./
Author:	Villoso, Enrico Palomera.
Description:	314 p.
Notes:	Source: Dissertation Abstracts International, Volume: 50-11, Section: B, page: 4939.
Contained By:	Dissertation Abstracts International50-11B.
Subject:	Biology, Zoology. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=9010412

Reproductive biology and environmental control of spawning cycle of weakfish, Cynoscion regalis (Bloch and Schneider), in Delaware Bay.
Villoso, Enrico Palomera.

Reproductive biology and environmental control of spawning cycle of weakfish, Cynoscion regalis (Bloch and Schneider), in Delaware Bay. - 314 p.

Source: Dissertation Abstracts International, Volume: 50-11, Section: B, page: 4939.

Thesis (Ph.D.)--University of Delaware, 1989.

Environmental influences on weakfish reproductive cycling and spawning behavior in Delaware Bay were investigated in 1979-1988. The seasonality of reproduction was determined from changes in gonadal maturity, percent ripe females, relative fecundity, condition factors and egg density distribution. Spawning of weakfish was protracted, extending from mid-May to July. The major peak occurred regularly between the last week of May and the first week of June each year, with minor sporadic pulses occurring from one to eight weeks after the major spawning episode. Primary peaks appeared to be associated with spring tides.Subjects--Topical Terms:

1018632
Biology, Zoology.

Reproductive biology and environmental control of spawning cycle of weakfish, Cynoscion regalis (Bloch and Schneider), in Delaware Bay.
LDR:03089nmm 2200337 4500 001 1825673
005 20061211115734.5
008 130610s1989 eng d
035 $a (UnM)AAI9010412
035 $a AAI9010412
040 $a UnM $c UnM
100 1 $a Villoso, Enrico Palomera. $3 1914671
245 1 0 $a Reproductive biology and environmental control of spawning cycle of weakfish, Cynoscion regalis (Bloch and Schneider), in Delaware Bay.
300 $a 314 p.
500 $a Source: Dissertation Abstracts International, Volume: 50-11, Section: B, page: 4939.
500 $a Professor in Charge: Malcolm H. Taylor.
502 $a Thesis (Ph.D.)--University of Delaware, 1989.
520 $a Environmental influences on weakfish reproductive cycling and spawning behavior in Delaware Bay were investigated in 1979-1988. The seasonality of reproduction was determined from changes in gonadal maturity, percent ripe females, relative fecundity, condition factors and egg density distribution. Spawning of weakfish was protracted, extending from mid-May to July. The major peak occurred regularly between the last week of May and the first week of June each year, with minor sporadic pulses occurring from one to eight weeks after the major spawning episode. Primary peaks appeared to be associated with spring tides.
520 $a Large females became sexually active earlier than smaller ones. Various size classes manifested from one to three spawning episodes per season. The duration of their spawning activity was inversely related to the size of the fish. All females with GSI of 10.0 or more were ovulated. Ovulated eggs comprised approximately 21% of the estimated fecundity with many mature oocytes remaining inside the ovary after the initial spawning burst was completed. Multimodal egg size distribution suggested fractional spawning in weakfish. Injections with human chorionic gonadotropin and luteinizing hormone-releasing hormone analogue demonstrated the capability of weakfish to spawn repeatedly during the season. Ovulation in hormone-treated females occurred 2 days after the initial injection.
520 $a Relative condition factor and hepatosomatic index were highest during the prespawning period and declined as the season progressed.
520 $a Spawning was mostly accomplished over a period of about three hours at twilight. Spawning was fairly localized, being more intense and common in the southwestern sector of Delaware Bay during the peak period.
520 $a Daylength was the major determinant for weakfish seasonal ovarian development with temperature acting to modify its effect. Ovarian growth was stimulated by long daylengths at both cold and warm temperatures. Under long daylength, recrudescence was stimulated at 12 $\ sp\circ $\ sp\circ $\ sp\circ $\ sp\circ
590 $a School code: 0060.
650 4 $a Biology, Zoology. $3 1018632
650 4 $a Biology, Animal Physiology. $3 1017835
650 4 $a Biology, Ecology. $3 1017726
650 4 $a Agriculture, Fisheries and Aquaculture. $3 1020913
690 $a 0472
690 $a 0433
690 $a 0329
690 $a 0792
710 2 0 $a University of Delaware. $3 1017826
773 0 $t Dissertation Abstracts International $g 50-11B.
790 1 0 $a Taylor, Malcolm H., $e advisor
790 $a 0060
791 $a Ph.D.
792 $a 1989
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=9010412