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Abstract Small-pelagic fishes are economically and ecologically important as they make up a large proportion of wild-caught fisheries and provide an important link between planktonic organisms and higher trophic level organisms such as piscivorous fishes, squid, seabirds and marine mammals. In the California Current Ecosystem (CCE), the distribution and abundance of Pacific sardine (Sardinops sagax) is influenced by both natural climate variability and exploitation. This study uses Generalized Additive Models to evaluate the effects of environmental forcing at multiple spatial scales (i.e. local, regional and basin) on sardine catch recorded at British Columbia (CAN), California (USA) and Bahía Magdalena (MEX). We find that the Pacific Circulation Index, sea surface temperature, upwelling strength, and primary productivity were the most influential factors explaining variability of sardine catch in the northeastern Pacific Ocean. Our CCE-wide analysis shows that regional scale environmental variability best explained catch rates of the Pacific sardine for California and Bahía Magdalena while basin-scale environmental variability did so for catch rates for British Columbia. [ABSTRACT FROM AUTHOR]

We investigated the environmental drivers of larval abundance of anchovy Engraulis encrasicolus and sardine Sardinops sagax in Algoa Bay, Eastern Cape (South Africa). This study comprised a pre-drought post-drought time period, comparing the responses of the fish larvae to different factors before and after the drought. The current study presents, for the first time, which environmental variables are affecting the anchovy and sardine larvae populations in the region. Easterly wind speed and zooplankton density were the only environmental variables that presented a significant change between the pre- and post-drought periods, increasing after the drought. Generalized additive models (GAMs) were used in order to explore the effects that environmental factors might have in the abundance of anchovy and sardine larvae in Algoa Bay. Specifically, the GAM that best explained the deviance of the anchovy larvae dynamics included the covariates rainfall, easterly wind speed, Chl a concentration, sardine larvae abundance and the interactions SST*Chla and sard*SST. The GAM best explaining sardine larvae abundance included only the easterly wind speed as a covariate. This model showed that there was a positive relationship between the higher values of wind speed and sardine larvae abundance. [ABSTRACT FROM AUTHOR]

Purse-seine vessels commonly interact with dolphins. The total number of dolphins accidentally killed in the world's purse-seine fisheries may be substantial, even if interaction rates are generally low. This paper describes an industry Code of Practice (CoP) that was established in Australian purse-seine fishery after an observer program detected high dolphin interaction rates that had not been reported in fishery logbooks. Key features of the CoP are search and delay procedures designed to prevent encirclements and release procedures that minimise mortalities. Extrapolation from observer data (3.9% of net sets observed), suggested that 449 dolphin encirclements and 423 mortalities occurred in 2004-05, the year before the CoP was established. A decade later, observer data suggest that annual encirclements and mortalities had been reduced by 87% and 97%, respectively. Searches were highly effective in detecting the presence of dolphins. Dolphins were not encircled in > 85% of net-sets made after searches determined that dolphins were absent from the fishing area. Opening the front of the net resulted in the successful release of all dolphins in > 86% of encirclement events. Discrepancies between interaction rates estimated from observer data and those recorded in logbooks have decreased over time. This study demonstrated that codes of practice that specify changes in fisher behaviour can be effective in mitigating the interactions of purse-seine fisheries with dolphins. The avoidance and release procedures documented in the CoP for the South Australian sardine fishery are simple and, if adopted in other purse-seine fisheries, could substantially reduce global mortality of dolphins. [ABSTRACT FROM AUTHOR]

Artificial Neural Networks (ANN) are adjusted to predict monthly landings of anchovy (Engraulis ringens) and sardine (Sardinops sagax) in northern Chile (18°21'-24°00'S). Fishing effort (FE), landings and twelve environmental variables are considered from 1980 to 2012. External validation for the best models using all variables showed an R2 of 95% for anchovy and 99% for sardine, with an efficiency of 0.94 and 0.96, respectively. The models were simplified by considering only FE and sea surface temperature (SST) from NOAA satellites (SST-NOAA). Using these variables, very similar fits were achieved, comparing with the previous models, maintaining their predictive capacity. Downscaled SST for A2 climate change scenario (2015-2065) obtained by statistical regionalization from the Community Climate System Model (CCSM3) from National Center for Atmospheric Research (NCAR) and three FE scenarios (2010-2012 average, + 50% and - 50%), were used as inputs for ANN simplified models. For A2 future climate change scenario (2015-2065) using 2010-2012 average FE as inputs, anchovy and sardine landings would increase 2.8% and 19.2% by 2065 respectively. With FE variations (-50%), sardine landings show the highest increase (22.6%) by 2065 when FE is decreased. [ABSTRACT FROM AUTHOR]

The stock structure of small pelagic fishes is difficult to determine due to their patchy distribution and complex movement patterns. We integrate genetic, morphological, otolith, growth, reproductive and fishery data collected over 60 years using a Stock Differentiation Index (SDI). The absence of strong separation (SDI > 0.66) of most adjacent sub-groups supports the hypothesis that sardine ( Sardinops sagax) in Australian waters is a meta-population, but with effective isolation of at least four stocks: south western coast (off Western Australia); Great Australian Bight and Spencer Gulf; Bass Strait and Port Phillip Bay (off Victoria and Tasmania); and eastern Australia. There is also evidence for sub-division of the stocks off Western Australia and the east coast. We examine age-related and inter-annual patterns of stock structure off South Australia and the east coast through integrated analysis of otolith chemistry and shape data. For the east coast, there were significant differences between northern and southern sub-groups for all three age cohorts examined. Fish were correctly classified to sampling region with a high degree of success (>80%), supporting the sub-division of the east coast stock suggested by the SDI. For South Australia, there were significant differences among two sub-groups for most cohorts examined across two sampling years. However, spatial discriminatory power was poor, with allocation success ranging from 48 to 64%. Results suggest that movements between the two South Australian sub-groups may vary among years, which is consistent with inconclusive SDI (0.5). Integrating historical data using a SDI is suitable for identifying fishery management units. Integrated analysis of otoliths from archival collections is useful for examining temporal variability in stock structure, which is also important for fisheries management. Our findings are relevant to fisheries where sustainability risks are increased by management arrangements based on assumptions that stock structure is absent or stable. [ABSTRACT FROM AUTHOR]

We examined spatial variability in meristic and morphological characteristics of the branchial basket of sardineSardinops sagaxcollected from four geographical regions around the southern African coast, namely Namibia and the South African west, south and east coasts. Our analysis tested the hypothesis of three putative sardine stocks off South Africa, one in each of the three geographical regions. We therefore collected fish data from Namibia to compare with South Africa, because sardine from the two countries are considered to be separate stocks. Morphometric measurements (gill arch length and gill raker spacing) and meristic data (number of gill rakers) were collected from the left side of the first gill arch from a total of 377 sardine, approximately equally divided between the regions. A multivariate general linear model with caudal length as covariate was used to assess differences among fish from the four regions and significant differences were observed, although not always consistently across all fish size classes. Small South Coast sardine had shorter gill arches than small West Coast sardine, but adults had gill arches of similar length, longer than those from Namibia and the East Coast. Small sardine from the South Coast had fewer gill rakers than small sardine from the West Coast, but larger fish had similar numbers of gill rakers, significantly more than sardine from Namibia and the East Coast. Sardine from the West and South coasts had similar gill raker spacings, which were smaller than those of fish from the East Coast and Namibia. Despite spatially and particularly temporally unbalanced sampling, we consider that these differences provide evidence of spatial variation in Benguela sardine phenotype and that it would support the hypothesis of discrete sardine stocks off Namibia and South Africa. The results are consistent with the hypothesis of three sardine stocks within the southern Benguela. [ABSTRACT FROM AUTHOR]

Spatial and temporal variation in infection of South African sardine, Sardinops sagax , by a metacercarial parasite was examined to test the hypothesis that the South African sardine population comprises multiple stocks. Samples of adult S. sagax were collected monthly from four commercial fishery landing harbours off the west and south coast and three indices of infection (infection prevalence, mean infection intensity and mean parasite abundance) were determined for each sample. Generalized linear models (GLMs) were used to assess the relative importance of putative stock (sardine caught off the west coast were assumed to be from the putative “western” stock whereas those caught off the south coast were assumed to be from the putative “southern” stock), season, year, fish size and all possible two-way interactions, where a binomial distribution was assumed for prevalence and a negative binomial distribution assumed for infection intensity and parasite abundance. The most parsimonious model for each index was selected based on Akaike's Information Criterion, and significant GLMs were derived for all three indices. Putative stock was the most significant contributor to explaining deviance seen in infection intensity and parasite abundance, and was the second most important contributor to explaining deviance seen in infection prevalence, with fish from the putative western stock having significantly ( p < 0.001) higher parasite loads compared to those from the putative southern stock. Temporal variability was also observed, with season and year also contributing significantly to all three models. Despite this temporal variability, the marked spatial difference in the distribution of infection of S. sagax by metacercariae supports the hypothesis of western and southern stocks of sardine off the coast of South Africa. The presence of infected large sardine off the south coast indicates that these putative stocks are not discrete and that some degree of mixing occurs between them, at least from the western to the southern area. [ABSTRACT FROM AUTHOR]

Two stocks of Pacific SardineSardinops sagaxmigrate seasonally and synchronously along the west coasts of Mexico, the USA, and Canada. Landings from the two stocks are currently combined in U.S. assessments of the northern stock, but the stocks may be differentiated by their associated seawater habitats, which are predominantly characterized by different ranges of sea surface temperature. We compared the combined and temperature-differentiated landings of the two stocks in each country for the period 1993–2011, demonstrating how different attributions of the landings affected the estimated annual fishing fraction (F) for the northern stock. Using combined or stock-differentiated landings and assessed biomasses, we found that the current harvest control rule (HCR) for Pacific Sardine has not consistently maintained a totalFbelow the U.S. target value because the “distribution” parameter (used to account for the northern stock's proportion in the U.S. Exclusive Economic Zone [EEZ]), has not adequately accounted for northern stock landings in Mexico and Canada. We propose a refinement to the HCR, giving explicit consideration to the summed landings in Mexico and Canada, to more optimally set the annual U.S. quota. The performance of our method was compared with (1) the values ofFthat would have been achieved during the federal management period (2000–2011) if the U.S. quotas had always been met and (2) the generally lower actual values ofFthat were calculated using the default HCR formulation (1993–2011). We demonstrate that application of our method would permit more U.S. fishing for Pacific Sardine when the northern stock is large and predominantly located in the U.S. EEZ and would curtail U.S. fishing when a large proportion of the stock is present and fished in the Mexican EEZ, Canadian EEZ, or both. Received December 12, 2013; accepted July 16, 2014 [ABSTRACT FROM AUTHOR]

The poleward flowing East Australian Current (EAC) drives sporadic upwelling, entrains coastal water and forms the western Tasman Front (wTF), creating a mosaic of water types and larval transport routes along south eastern Australia. The spatial distribution, otolith chemistry and growth rates of larval sardine ( Sardinops sagax) were examined to infer spawning location and larval transport. A gradient of increasing larval size from north to south along the shelf was not detected but was evident between the shelf and offshore in the wTF. Here larvae were larger and older. Based on the occurrence of newly hatched larvae, spawning by S. sagax between southern Queensland and mid New South Wales (NSW) was more extensive than previously reported. The otolith chemistry from two wTF larval size classes differed, implying different origins. The otolith chemistry of wTF post-flexion larvae was similar to larvae from northern NSW, whereas wTF flexion larvae were similar to larvae observed nearby from mid-NSW. Two possible larval transport routes, direct and indirect, are inferred from otolith chemistry, current velocities and a previously published particle tracking study. Either larvae from northern NSW were advected south and entrained with younger larvae directly into the wTF, or larvae from a range of shelf regions were advected around the southern edge of an anticyclonic eddy, to join younger larvae directly entrained into the wTF. Based on the co-occurrence of larval ages and sizes in the wTF and their advection routes, the wTF appears to be an important larval retention zone. [ABSTRACT FROM AUTHOR]

Particle-tracking experiments were performed to infer the distribution of larvae of the Japanese sardine ( Sardinops melanostictus) and to detect effects of transport environment on sardine recruitment, using the output of a high-resolution ocean general circulation model and observed data of sardine spawning grounds during 1978-2004. By the 60th day following spawning, approximately 50% of the larvae had been transported to the Kuroshio Extension ( KE). Whereas the spawning period and grounds changed markedly in relation to the stock level, the proportion of larvae transported to the KE remained relatively constant and no significant correlations were found between sardine recruitment and the transport proportion. Instead, the recruitment was found to be correlated with physical parameters including the mixed layer depth and the sea surface temperature along several major transport trajectories of sardine larvae. The correlations were most significant for the trajectories in the region 0.5° south to 1° north of the Kuroshio axis (defined as the location of velocity maxima at each longitude) and for larvae spawned in February and March during the high stock period (1978-94), and for larvae spawned in March and April during the low stock period (1995-2004). [ABSTRACT FROM AUTHOR]

de Moor, C. L., Butterworth, D. S., and De Oliveira, J. A. A. 2011. Is the management procedure approach equipped to handle short-lived pelagic species with their boom and bust dynamics? The case of the South African fishery for sardine and anchovy. – ICES Journal of Marine Science, 68: 2075–2085.Worldwide, small shoaling pelagic fish manifest rapid and substantial natural changes in abundance. Is the application of a management procedure (MP), evaluated using simulation tests [i.e. a MP approach otherwise known as management strategy evaluation (MSE)], to recommend total allowable catches (TACs) with constraints desired by industry on the extent of interannual changes viable for such resources, particularly given the customarily lengthy MP evaluation process? This question is examined by considering the rapid boom and then bust situation that arose for the South African fishery for sardine (Sardinops sagax) and anchovy (Engraulis encrasicolus) across the turn of the century. Novel adaptations to the MP in place at the time of the boom allowed enhanced resource use during the boom period without compromising the risk of unintended depletion of the populations. Importantly a two-tier threshold system allowed the normal constraints on the maximum extent of interannual TAC reduction to be modified when TACs rose above the specified thresholds. The general protocol underlying the application of MPs for South African fisheries proved sufficiently flexible for the approach to continue to be applied, despite the unanticipated rapid fish population boom and then bust experienced. [ABSTRACT FROM PUBLISHER]

Abstract: The effects of freezing on the morphometrics of sardine Sardinops sagax were studied. Results were variable depending on the length of the freezing period, but all fish showed significant (p <0.001) decreases in both caudal length and wet body weight compared to initial measurements taken from unfrozen fish. The absolute weight loss of sardine ranged between 0.256 and 0.868g, which corresponded to a relative weight loss between 0.86 and 2.49%. The absolute loss in caudal length ranged between 0.281 and 0.458cm, whereas the relative loss in caudal length ranged between 1.57 and 2.54%. The effect of freezing duration on morphometric measurements was variable, and whereas shrinkage was most common, no effect was observed in a number of cases. Most of the morphometric measurements showed small changes and, if they decreased, the decrease was gradual. Only one morphometric measurement (LM 12, the distance between the snout and the top of the head) showed a significant increase in half of the eight freezing periods. The relevance of these results to studies of morphological variability in fish is discussed. [Copyright &y& Elsevier]

Abstract: The Pacific sardine (Sardinops sagax) supports one of the most important fishing industries of the northeastern Pacific Ocean (NPO). The recruitment of juveniles in the NPO has shown fluctuations in recent decades; this has been attributed to variations in the spawning stock biomass (SSB) and to the oceanographic conditions within the California Current system (CCS). In this study, these hypotheses are tested by fitting three different stock–recruitment (SR) functions into different models using data of recruitment and SSB of Pacific sardine in three regions of the NPO: Magdalena Bay (MB), Ensenada (EN), and north Pacific (NP). To quantify the plausibility of each model, given the data and the set of three models, the Akaike weight of each model was calculated. The selection of the best model within each area was done by minimizing the small-sample, bias-corrected form of the Akaike information criterion. Through this approach, the MB and EN fisheries fitted both the asymptotic Beverton–Holt and dome-shaped Ricker models. These results agreed with prior evidence that recruitment of Pacific sardine has a density-dependent mortality term for eggs and juvenile stages, related to the total SSB and cohort size. To test environmental influence on sardine recruitment principal component analysis was undertaken. The first principal component group was determined by El Niño–La Niña episodes; the second, by the upwelling index. Upon incorporation of these principal components into the SR models, the recruitment of the sardine throughout the CCS was differentially affected, e.g., warm episodes in MB negatively affected recruitment, whereas in the EN and NP regions, the effect was positive. [Copyright &y& Elsevier]

Abstract: In this study the performances of computational neural networks (CNNs), multiple linear regressions (MLRs) and generalised additive models (GAMs) to predict Pacific sardine (Sardinops sagax) landings and to analyse their relationships with environmental factors in the north area off Chile were studied. For this purpose several local and global environmental variables and indexes (sea surface temperature, sea level and Ekman transport index in the Chilean coast and, sea surface temperature in the area Niño 3+4 and Niño 1+2, and the south oscillation index) were considered as inputs or independent variables. Additionally, several CNNs were calibrated and validated adding the anchovy (Engraulis ringens) landings in the same area as model inputs. The time lags of the variables considered were selected through analysis of the non-linear cross-correlation functions and an alternative form of sensitivity analysis based on the approach of the missing value problem. The analysis of error measures with validation data set showed that the best results were obtained when local and global variables were used separately and combined with anchovy landings. Globally, the best result was given by a CNN with 18 input variables (model CNN 6(II) which only considered global variables and anchovy landings) and 10 neurons in a hidden layer. For this configuration the explained variance was slightly higher to 86% which supposed a standard error of prediction of 7.66%. These results were significantly better than those obtained with MLRs and GAMs. The strong correlation between predicted and observed sardine landings suggests that CNNs captured the trend of the historical data. Also, the generalisation capacity together the sensitivity analysis allowed us to identify the variables with a high weight in the model and partially to interpret the statistical functional relationships between these environmental variables and sardine landings. [Copyright &y& Elsevier]

Propagating epizootics due to Pilchard herpesvirus (PHV) occurred in the Australian population of pilchard, Sardinops sagax neopilchardus (Steindachner) (Clupeidae), in 1995 and 1998–99, with up to 60% losses. No mortality events have been evident in the ensuing 7 years, one reason for which could be that PHV is now endemic. During 2004, a survey was conducted to establish if PHV was present in pilchards in Australia. The pilchard is a highly active, pelagic schooling fish which is found in subpopulations, creating difficulties for the conduct of surveys. It occurs in Australian coastal waters and embayments below about 25 °S latitude, feeds on plankton and is predated by birds, mammals and larger fish. It reaches sexual maturity at 2 years of age, spawns at sea, enters embayments when about 5 months old and returns to sea when about 1 year old. It may live for 6–9 years, reaching a maximum length of 200 mm. It forms schools and may travel up to 30 km per day. Pilchards aggregate in mobile shoals of fish containing large highly mobile schools, which interact randomly and exchange individuals. Four subpopulations were defined for the purposes of this survey based on differences in biological characteristics: south-eastern Queensland/northern New South Wales (NSW), Victoria/South Australia (SA), south coast Western Australia (SWA) and west coast Western Australia (WWA). Specimens were obtained from the catch of commercial fishermen using random sampling where possible. Polymerase chain reaction (PCR) for the detection of PHV was performed after appraising the suitability of all available tests according to their impact on sample size requirements, total survey costs and logistical constraints. In the analysis, estimates of true prevalence (TP) of infection and 95% confidence limits were adjusted from the apparent prevalence estimates provided by PCR results. Percentage TP of PHV and corresponding 95% confidence intervals for the four subpopulations: NSW, SA, SWA and WWA were thus estimated as 0 (0–1.5), 31 (22–43), 42 (31–55) and 29 (20–41), respectively. PHV is now endemic in Australian populations of pilchard. Implications of the findings for fisheries management are discussed. [ABSTRACT FROM AUTHOR]

This study assessed the stock-recruitment relationship (SRR) for the Japanese sardine Sardinops melanostictus in the North-western Pacific. Of the 20 SRR models investigated, the Akaike information criterion (AIC) was the minimum (AIC = 551.2) when the data were separated into two groups (A and B) and the log-normal distribution was applied as the error term. Group A was constructed with SRR data from 1976–1987 and 1992–2004. Group B consisted of data from 1988–1991. The AIC minimum model was R = 22.8 S × e ε for Group A, where R, S, and ε denote the recruitment of sardine (individual number of 0-year old fish), spawning stock biomass (SSB), and error term, respectively. This model indicated that recruitment was proportional to the SSB and that no density-dependent effect operated over the range of SSB investigated (51 000–11.3 million t). Recruitment was markedly higher (lower) when the sea surface temperature (SST) of the Kuroshio Extension area in February was low (high). The essential SRR can simply be expressed as R = 22.8 S × e ε with the level of recruitment deviating from the model to a greater or lesser degree depending on the environmental conditions. [ABSTRACT FROM AUTHOR]

The article discusses the study on sardine fisheries in the Gulf of California. Evaluated is the sustainable management of the fishery as well as the prediction of total fishery catch and catch per unit effort (CPUE) of Pacific sardine. Tackled is the reproductive ecology of seabirds, along with the advancement of the outcome of fishing efforts.

Abstract An Empirical Biomass Model for the Japanese sardine, Sardinops melanostictus , was developed on the basis of the relationship between February sea surface temperature (SST) in the Kuroshio Extension (30–35°N, 145–180°E) and the mortality coefficient during the period from egg to age 1, observed in 1979–94, to examine the long-term variation of biomass. The periods of the good and bad catch, the year of the biomass peak, and the speed of the biomass decline in the period from 1957 to 1994 were successfully reproduced, except for the biomass increase in the early 1970s. When the model also included with a density-dependent effect, the whole history of the observed catch during 1957–94 was almost perfectly reproduced. These results suggest that the environment in the Kuroshio Extension region, represented by winter–spring SST, is regarded as a leading factor for determining fluctuations of the sardine biomass in the long term, and that the density effect has a secondary contribution. [ABSTRACT FROM AUTHOR]

We examined the distribution of sardine larvae relative to environmental conditions with the purpose of identifying and characterizing habitat that encourages high larval growth and survival, based on the 1983–1998 surveys of the California Cooperative Oceanic Fisheries Investigations (CalCOFI). Long-term averages show that sardine ‘survivors’ (spatially aggregated larvae ≥ 18 days old) were most abundant offshore, whereas sardine egg density, chlorophyll biomass and zooplankton volume were greatest inshore. In contrast, mesoscale eddies, observed in remotely sensed sea surface temperature imagery, were found only in offshore regions. To further examine the link between eddies – which often result in locally elevated chlorophyll and zooplankton – and sardine survival, we compared the distribution of larvae and eddies survey by survey. Sardine survivors were most abundant offshore in only one-quarter of the research surveys, and when they were most abundant offshore they were associated with eddies. This indicates that the offshore eddy habitat produced exceptionally large numbers of survivors, as evidenced by the disproportionate effect on the long-term average. [ABSTRACT FROM AUTHOR]