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Fishes caught from depth often suffer from barotrauma, which can result in high mortality rates (close to 100% for some species) when released at the surface. To mitigate for this, the recreational fishing community pro-actively developed several different types of descending devices designed to assist unwanted or prohibited fish back toward the bottom for release. Post-release survival using recompression techniques has been documented for some species, which has allowed fisheries managers to begin revising estimates of total fishing mortality in some cases, but the effectiveness of the different commercially-available descending device types has not been quantified. We conducted 24 Commercial Passenger Fishing Vessel charters at 11 sites along the coast of California, and invited volunteer recreational anglers aboard the charters to test the effectiveness of five different commercially available device types, and respond to a survey of their device preferences. During release, all fish were descended either to 46 m (150 ft) depth or directly to the bottom, whichever depth was shallower. While there were some significant differences between device types, all devices were effective for releasing rockfishes back to depth. Initial post-release mortality (defined as all mortality events observable from the vessel while fishing) across all devices was relatively low (7.5%) in capture depths less than 100 m, but increased significantly to 16.4% at capture depths from 100 to 135 m. Our results suggest that rockfishes should be released at least half-way to the bottom (preferably directly to the bottom) for the device to be effective in minimizing post-release mortality. The time required to use the devices averaged under three minutes regardless of device type, meaning that all device types could be used efficiently on deck, but anglers showed a clear preference for the SeaQualizer™. This device produced some of the lowest release error rates and lowest initial post-release mortality of rockfishes aboard the charters, so angler preference coincided with device effectiveness. Collaborating with the recreational fishing community was an extremely important aspect to this study, provided more robust results, and fostered working relationships that can be built upon in future research projects.

An understanding of the reproductive biology of a species is fundamental to successful management of fish stocks. Rockfish (Sebastes spp.) have complex reproduction, being viviparous and generally late to mature, often with extended adolescent periods characterized by abortive maturation events. Furthermore, whereas the majority of Sebastes species in the California Current region produce one brood of larvae annually, several are known to produce more than one, though no stock assessments have yet considered the impact multiple brooding may have on population spawning potential for these species. We documented abortive maturation and examined the prevalence and size-dependent and regional patterns of multiple brooding using macroscopic evaluation and detailed histological analysis of ovaries from a model species, chilipepper (S. goodei), collected off Central and Southern California. We modeled the size-related maternal effect on the probability of multiple brooding, and quantified size-dependent fecundity relationships. Our results indicate that the most robust estimation of reproductive output, as a function of the fecundity-length relationship, is improved for chilipepper when multiple brooding is incorporated, due to the greater probability of additional broods, and thus greater spawning potential, in larger females.

Estimates of fecundity at size are a key component of age-structured population dynamics models such as those used for stock assessment purposes. Fecundity-length relationships for many exploited fish stocks are often poorly understood due to small sample sizes and high levels of intrinsic variability among individuals. Several species in the genus Sebastes match this description, and are important components of commercial and recreational fisheries off the U.S. West Coast. We used a hierarchical Bayesian modeling framework for simultaneous estimation of parameters in the fecundity-length relationships for 29 species of rockfish while accounting for variability within and among subgenera. Hierarchical models that account for subgeneric phylogenetic structure and variability among species outperformed models that treat all species in the genus as exchangeable or ignored variation among species within a subgenus, based on a predictive information criterion. Our results confirm that weight-specific fecundity increases with size in nearly all Sebastes species, and that the assumption of proportionality between mature female biomass and total egg production is inappropriate for most Sebastes stock assessments. Benefits of the hierarchical framework include prediction of fecundity-length parameters at the genus, subgenus, and species level, as well as predictive distributions for unobserved Sebastes species.

a b s t r a c t A comprehensive understanding of reproductive biology is fundamental to the accurate assessment of a given stock's spawning potential relative to the unfished level. Such an understanding is particularly important given the growing recognition of size, age or weight dependent relative fecundity (Фrel, eggs per kg of female weight), or other maternal effects that may demonstrate a relatively greater contribu- tion of specific demographic components of a population toward reproduction. However, size-specific data on Фrel, or other data on maternal effects on reproductive output, are not always available for many stock assessments because intensive efforts are required to collect such data. In the absence of data, the assumption of no size-specific Фrel relationship is typically made, which can lead to bias in esti- mating stock status and related management parameters. We examined effects of misspecifications of size-specific Фrel functions on estimated stock assessment parameters and related management quan- tities using two stocks as case studies and three sets of simulation models, chosen to represent wide ranges of life and fishing histories. The results showed that misspecification effects were relatively small when stocks were less depleted (e.g. 75% of virgin spawning output), but could lead to more substantive misspecifications in more depleted stocks with slower growth and lower mortality rates. For example, we found that stock was estimated to be as much as 20% less depleted if a strong size-specific Фrel exists in a population, but no size-specific Фrel is used in the model. This represents a non-trivial shift in the perception of status for most stocks. The results also showed that overestimating the strength of the size-specific Фrel function in stock assessment models led to smaller estimation errors in assessment outputs compared to underestimating the size-specific Фrel. The results are insightful with respect to the importance of gathering data on size-dependent Фrel and other aspects of reproductive ecology, as well as with respect to the nature of assumptions that are made with regards to reproductive ecology in data limited situations. Published by Elsevier B.V.

Over 60 species of rockfish (Sebastes spp.) reside off the coast of California, many of which are economically important to both recreational and commercial fisheries. Rockfish are live-bearers with a diverse array of reproductive strategies. Understanding the reproductive potential of an exploited stock is critical to assessing the health and status of a fishery. We investigated the reproductive ecology of four rockfish species to examine species contrasts and to determine spatial and maternal-size effects on reproductive potential. Females were sampled during the winter parturition season (November through March) of 2009 through 2012. Maternal length and somatic weight were positively correlated with relative fecundity (larvae per g somatic weight) in all four species, indicating a disproportionately greater reproductive output by larger, older females. Fecundity estimates in Chilipepper, S. goodei, and Yellowtail rockfish, S. flavidus, varied regionally, but did not significantly differ over time within the years sampled (sample sizes for Speckled, S. ovalis, and Blackgill rockfish, S. melanostomus, were too small to allow spatiotemporal comparisons). Two reproductive strategies were evident as Yellowtail and Blackgill rockfish produced a relatively highly fecund, single brood of smaller-sized larvae annually, in contrast to Chilipepper and Speckled rockfish, which produced larger-sized larvae with lower fecundity. In some regions multiple broods were common, complicating estimates of annual fecundity for these two species. There was some evidence that egg production was positively correlated with female condition, indicating that environmental variability in oceanographic conditions and productivity may drive changes in fecundity and reproductive strategy (i.e., single versus multiple broods).

Chilipepper rockfish ( Sebastes goodei ), a long-lived, highly fecund commercial species in the California Current ecosystem, contend with a variable environment on several time scales. Using a bioenergetics model, we simulated alternate strategies of energy allocation by female chilipeppers under variable conditions, and examined resulting patterns in age-dependent size and fecundity. Variable conditions consisted of single climate events (one anomalous year, one 4-year regime shift, or one 10-year regime shift) that occurred at different points over the lifespan of the fish and were either “poor” or “good” relative to baseline conditions. Poor years or regimes reduced growth and fecundity, while good years or regimes increased growth and fecundity. Fecundity losses during poor conditions could be mitigated by partially or fully reallocating energy from gonadal production into somatic growth, thereby increasing potential fecundity in future years. However, when mortality was incorporated, those energetic re-routing strategies only increased lifetime reproductive output if we assumed that old (≥age 8) females produce more viable larvae than young females, and if the event occurred prior to age 8. Young females also increased output of larvae beyond age 8 if they skipped spawning or reallocated reproductive energy during good conditions, instead investing the surplus energy into additional somatic growth and enhancing future fecundity. Our results are consistent with recent estimates of growth rate variability in the chilipepper population, and with observations of young females of other rockfish species skipping spawning during poor conditions. Models like this may help improve stock assessment parameters and biological reference points for species with environmentally driven variability in size at age.

The periodicity of otolith growth increments (opaque and translucent zones) from adult red snapper (Lutjanus campechanus) was examined through a mark and recapture study (2005–2010), and laboratory holding of hatchery reared red snapper over a 2 year period (2002–2004). Wild red snapper (n = 295) were caught hook-and-line, marked with anchor tags, injected with oxytetracycline dihydrate (OTC), and released in the Gulf of Mexico 15–40 km south of Dauphin Island, Alabama. Marked fish were recaptured up to 2.8 years after release (n = 35) and sagittal otoliths were dissected, sectioned and examined under white and blue-violet light. The number of opaque growth zones past the OTC mark was compared to time at liberty for each fish and supported an annual periodicity of growth increment formation. Also, most (87%) of the hatchery reared fish showed two opaque zones that supported an annual increment formation rate. However, an unusual timing of opaque zone formation was shown for mark-recaptured fish. Based on known timing of OTC marking, otoliths from mark-recapture fish showed opaque zone formation from late summer (August) to early winter (December). This fall formation of opaque zones is in contrast to previous studies and its timing may relate to the end of spawning for this species.

Morphological changes in otolith shape with age, of young (