Smallscale weakfish (Cynoscion microlepidotus), King weakfish (Macrodon ancylodon) e
Pacora (Plagioscion surinamensis) are demersal sciaenids, largely distributed in the Brazilian
coast. These species are important fishing resources. This study has the objective of
describing aspects of the reproductive biology of these species caught in areas near to the
harbors of Itaqui (Maranhão) and Miramar (Pará). For each species, the reproductive stages
were macro and microscopically described, the length at first maturity, sexual proportion by
month and size, the breeding period and type of spawning was also evaluated. Data were
collected in a bimensal basis from December 2005 to October 2006. It was examined 247
individuals of C. microlepidotus, 253 of M. ancylodon and 251 of P. surinamensis.
Individuals of C. microlepidotus, M. ancylodon and P. surinamensis measured from 175 to
780 mm, 187 to 399mm and 220 to 590 mm of total length, respectively. The relationship
total length (mm) and total weight (g) for females, males e sexes grouped were highly
significant for the three species, with negative alometry for C. microlepidotus and positive
alometry for M. ancylodon and P. surinamensis. The length of first maturity (L50) for C.
microlepidotus, considered grouped sexes was 260.8 mm, 235mm for males and 321mm total
of length for females. For M. ancylodon, L50 for grouped sexes was 210.5 mm, 201.6mm for
males and 221.8mm for females of total length. For P. surinamensis, L50 for grouped sexes,
for males and for females were 279 mm, 305mm and 269mm of total length. Sexual
proportion, considering the total number of individuals favored females for M. ancylodon
(1male:3female) and favored males for P. surinamensis (2,02male:1female). For C.
microlepidotus, male: female proportion was equivalent. Macroscopically, gonads of the three
species were classified as Immature (A), Maturing (B), Mature (C) and Spawned/Spent (D),
however, when analyzed microscopically, the stage B were sub-divided in initial and final
maturing. The macro and microscopical evaluation of gonads indicated a prolonged spawning
season, with reported peaks in June- August and December- February, coinciding to the
rainfall transition period. The studied species complete their life cycle entirely near the
harbors of Itaqui and Miramar, leading these areas to be classified as extremely sensitive
especially when referring to possible oil spill.
|
