Temporal variation in male traits, nesting aggregations and mating successin the peacock blenny

At the beginning of the breeding season male Salaria pavo that have eggs in their nests are larger, have more developed anal glands and less intense e ye-spots and are located in breeding aggregations. These differences cease to occur From the peak of the breeding season (June-July) onwards. Two scen arios are presented that may explain these results: (1) smaller and younger males may begin to breed later devoting part of the warm season to growth; (2) females may cease to be selective as the nesting space begins to be sa turated with eggs. These results raise one methodological and one conceptua l question. The search for correlates of male reproductive success must cov er different phases of the breeding season to capture the overall dynamics of the processes involved. The operational sex ratio for cavity-spawning fi shes should take into account the availability of spawning sites rather tha n just counting the sexually mature members of each sex. (C) 1999 The Fishe ries Society of the British Isles.