Preliminary Study On Biological Characteristics Of Amoya Pflaumi In Jiaozhou Bay

The biological characteristics, such as growth and mortality, reproductive habitsand feeding habits, of Amoya pflaumi in Jiaozhou Bay were studied in this paper.According to the data obtained from investigation by bottom trawl in the centralJiaozhou Bay from December2008to August2009, some biological characteristics ofAmoya pflaumi were analyzed, such as growth, mortality, productive habit, and so on.A total individuals of962were sampled. However, the study of feeding habits ofAmoya pflaumi was on the basis of data, which was obtained from investigations bybottom trawl in Jiaozhou Bay on May and November,2011. A total individuals of143were sampled. We had preliminary knowledge of biological characteristics of Amoyapflaumi in Jiaozhou Bay. The main results of this study were as follows:1. Based on the biological data obtained from from investigation by bottom trawlin Jiaozhou Bay, growth and mortality parameters of Amoya pflaumi were estimatedby the FiSAT Ⅱsoftware, and then the fishery stock conditions of Amoya pflaumiwere analyzed. The results showed that:（1） Length and weight composition of Amoya pflaumi were both unimodal.（2） The relationship between standard length and body weight was expressed asW=7×10^-6SL^3.1442（R²=0.9311）.（3） The growth parameters of von Bertalanffy formula estimated with ELEFANⅠ in FiSAT Ⅱ package wereL_∞=72.8mm, W_∞=5.01g, k=0.44a^-1, and t₀=-0.46a.（4） Mortality coefficients were M=1.01, F=2.74, Z=3.75, and the exploration rateis E=0.73.（5） Under the current fishing mortality F=2.74, the first capture size and weightwere29.5mm and0.66g, respectively. According to the growth parameters, theinflexion point of age was2.14year, and the inflexion point of length growth was49.6mm. The critical age and critical length were1.5year and42.1mm respectively. （6） The length at first capture (L₅₀) of Amoya pflaumi was43.6mm under thecurrent bottom trawl.2. The results of reproductive biology were summarized as follows:（1） By analyzing the monthly changes in the percentage of females in differentgonadal stages, it was found that the major spawning season of A. pflaumi was inJune.（2） The absolute fecundity of A. pflaumi ranged from1377to6157eggs, with amean value of3689±365S.E. eggs. The relative fecundity to standard length （FL）varied from38to124eggs/mm, with an average value of81±7S.E. eggs/mm. Therelative fecundity to body weight （FW） varied from1622to4354eggs/g, with anaverage value of2780±196S.E. eggs/g.（3） The size of egg diameter in Ⅳmaturity stage ovary ranged from0.375to0.636mm, with a mean value of0.501±0.002S.E. mm. The egg diameter distributionin Ⅳ maturity stage ovary was unimodal with a dominant range of0.450～0.550mm.（4） The size at first maturity （L0.5） of Amoya pflaumi was estimated as41.8mm,and the age at first maturity was1.48year.3. The results of feeding habits of Amoya pflaumi were summarized as follows:In this study,143stomach contents were analyzed. More than23species wereidentified in the diet. Lamellibranchia （IRI=466.64,%IRI=27.50%） and Amphipoda（IRI=390.63,%IRI=23.03%） were the most important prey groups in the diet.Polychaeta （IRI=286.17,%IRI=16.87%） constituted the second most important preygroups. Monoculodes sp.（IRI=265.27,%IRI=15.64%） and Calanus sp.（IRI=176.81,%IRI=10.42%） were the most important prey species. Dosinia gibba（IRI=135.94,%IRI=8.01%）, Moerella jedoensis （IRI=124.16,%IRI=7.32%）, Sandaliarhodia （IRI=99.53,%IRI=5.87%）, Moerella iridescens （IRI=90.08,%IRI=5.31%） andAmpelisca sp.（IRI=88.38,%IRI=5.21%） are also the important prey species in thediet of Amoya pflaumi.