Population differentiation and relationships among 6 natural rockfish populations collected from northern coastal seas around Japan were assayed using microsatellite DNA loci. Seven loci examined were polymorphic in all populations. The number of alleles per locus ranged from 6.7 to 9.3, and the average of observed and expected heterozygosity ranged from 0.63 to 0.68, and from 0.66 to 0.69, respectively. The observed genotype frequencies at each locus were almost in agreement with Hardy-Weinberg expectations with two exceptions (P <.05). The allele frequencies of 16 population pairs were significantly different (P <.05). Genetic distance (D(A)) between 6 populations ranged from 0.03 to 0.08. According to a neighbor-joining tree generated from the D(A) values, the 6 populations fell into 3 clusters. These clusters were correlated with the geographical positions of each population; larval dispersions due to water current were also found to have an effect on these results.

No abstract

Even if artificial reef studies heavily refer to the distinction between resident and transient species, there is still no widely-shared available method to distinguish objectively these two groups. Such an absence makes any comparison between studies difficult. This study aims to test whether the four objective distinction methods successfully applied to a 21-year-long time-series on fish assemblage in an English estuary may be as successful when applied to marine artificial reefs. For such a purpose, we tested each distinction tool separately with reference to four different artificial reef fish assemblage datasets. Three of them were drawn from the literature. Results indicate that none of these tools, used either individually or collectively, provide an efficient solution to distinguish resident species for the four datasets considered. We suggest that one of the major reasons for this failure may lie in the relative sampling size. Nonetheless, as these four datasets are representative of the datasets generally reported in the literature, tools capable of distinguishing reliably and efficiently resident from transient species along artificial reefs have yet to be developed. However, such a development requires fish residence to be previously and accurately defined by artificial reef scientists and managers.

No abstract

No abstract