The intense exploitation since 1972 of the formerly only slightly exploited protogynous hermaphroditic fish Pagrus pagrus (L.) in southern Brazil has led in less than a decade to the collapse of the fishery, with no recovery four decades later. In this study we analized the age structure, growth, reproduction and mortality of the species were studied based on samples collected from 1976 to 1985 to provide a baseline before the onset of overexploitation. Maximum estimated ages were 21 and 26 years based on scale and otolith readings, respectively. Mean total length (TL) at age did not differ between males and females, while hermaphrodites were smaller. The von Bertalanffy growth coefficients for all fish (immature, females, hermaphrodites and males) were L∞ = 447 mm, k = 0.204 and t0 = −1.134 yr. Change in growth was observed during the study period. Females were dominant at all sizes, hermaphrodites were only present up to intermediate sizes, and males, despite being infrequent at small sizes, made up over 40% among the larger specimen (TL > 400 mm). Spawning took place mainly in late spring and condition factors were lower after spawning. Natural mortality was estimated as M = 0.173 yr−1 based on the von Bertalanffy growth parameters. Total mortality (Z) and exploitation rate (E) estimated from catch curves of fully recruited red porgies aged five to ten years increased from 0.24 yr−1 and 28% before 1973 to 0.49 yr−1 and 63% in the following years. Two distinct scale and otolith patterns, one with well-marked annuli and another with faint or absent annuli, suggested that the red porgy stock off southern Brazil might not be homogeneous and may include subpopulations that do not fully mix.

The population dynamics of the stout reef octopus, Octopus insularis fished with longlines of pots in mid-shelf waters of north-eastern Brazil was studied based on fishermen's logbooks and onboard monthly fishing trips from September 2009 to August 2010. Specimens marked with oxytetracycline kept in tanks for up to 21 days provided evidence of the daily deposition of growth increments in the lateral wall of the upper beaks. Sampled specimens weighed 50–1280 g and had 43–172 daily growth increments. Compared with congeneric species from higher latitudes, O. insularis grows faster and has a shorter longevity in the north-eastern Brazil tropical environment. Total catches and catch-per-unit effort were substantially higher in the dry season, with less wind and cooler temperatures. The presence of larger specimens was seasonal, correlated with the chlorophyll-a levels recorded six months earlier. The year-round presence of mature females and males, spawned females, and egg masses attached to the pots, were considered evidence of migration of small and young specimens from coastal areas towards the 20–40 m depth range for reproduction. Annual landings attained ~200 tonnes (2005–2010). Although recent landing statistics are missing, fishermen interviewed in 2021 claimed that the fishery was still profitable. It is suggested that, despite the lack of management, the fast growth, year-round reproduction and limited market for this relatively small octopus, prevented the fishery from collapse and reinforces the current view of the high resilience of cephalopod fisheries.

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The surf zone is a highly dynamic environment subject to seasonal fluctuations which could impose restrictions to the development of juvenile fish. The allometric condition factor index (K) provides a value of 'well-being' for fish, been used to compare populations under different environmental conditions. The aim of this study concerned on evaluate the effect of seasonality on surf-zone juvenile fish' K. Along two years the K values of the main fish species were analyzed. The temperature and abundance were also reported. We compared data between cold and hot seasons to test the effect of seasonality. A total of 955 individuals were collected, totaling 20 species. Despite the surf zone instability, most fish species showed a stable K regardless of season. We found that the condition factor in neritic Atherinella blackburni, Mugil brevirostris, Trachinotus carolinus and Trachinotus goodei did not vary. Only a demersal species, Menticirrhus littoralis, shown the lowest condition factor in the hot season, coinciding with maximum water temperature. We discussed how the surf zone provides conditions for the development of fish and reinforce the importance of this environment as a breeding site.

Otolith shape analysis is a powerful method for fish stock identification. We compared the otolith shape of Pagrus pagrus (Linnaeus 1758) along with its distribution in four south‐western Atlantic regions where it is commercially fished: Rio de Janeiro, Rio Grande do Sul in southern Brazil, the Argentine‐Uruguayan Common Fishing Zone (UA) and the Argentinian Exclusive Fishing Zone (AR). Otolith shapes were compared by Elliptical Fourier and Wavelet coefficients among specimens in a size range with similar otoliths, morphometric parameters and ages. Four potential stocks were identified: one in the AR, a second along the UA which included specimens from southern Brazil with well‐marked opaque bands in its otoliths (MRS), the third in southern Brazil with faint or absent opaque bands in its otoliths (FRS) and the fourth along Rio de Janeiro. The difference in the otolith shape among regions followed differences reported using other stock identification techniques. The similarity between otoliths from UA and MRS (ANOVA‐like, P > 0.01) can be explained by seasonal short‐range migrations. Otoliths shape differences between MRS and FRS (ANOVA‐like, P < 0.01) suggest that P. pagrus does not form a homogeneous group in southern Brazil.