Biomass and reproduction of Pacific sardine (Sardinops sagax) off the Pacific northwestern United States, 2003–2005

The Pacific sardine (Sardinops sagax) is distributed along the west coast of North America from Baja California to British Columbia. This article presents estimates of biomass, spawning biomass, and related biological parameters based on four trawl-ichthyoplankton surveys conducted during July 2003 –March 2005 off Oregon and Washington. The trawl-based biomass estimates, serving as relative abundance, were 198,600 t (coefficient of variation [CV] = 0.51) in July 2003, 20,100 t (0.8) in March 2004, 77,900 t (0.34) in July 2004, and 30,100 t (0.72) in March 2005 over an area close to 200,000 km2. The biomass estimates, high in July and low in March, are a strong indication of migration in and out of this area. Sardine spawn in July off the Pacific Northwest (PNW) coast and none of the sampled fish had spawned in March. The estimated spawning biomass for July 2003 and July 2004 was 39,184 t (0.57) and 84,120 t (0.93), respectively. The average active female sardine in the PNW spawned every 20–40 days compared to every 6–8 days off California. The spawning habitat was located in the southeastern area off the PNW coast, a shift from the northwest area off the PNW coast in the 1990s. Egg production in off the PNW for 2003–04 was lower than that off California and that in the 1990s. Because the biomass of Pacific sardine off the PNW appears to be supported heavily by migratory fish from California, the sustainability of the local PNW population relies on the stability of the population off California, and on local oceanographic conditions for local residence

Fecundity, egg deposition, and mortality of market squid (Lolilgo opalescens)

Loligo opalescens live less than a year and die after a short spawning period before all oocytes are expended. Potential fecundity (EP), the standing stock of all oocytes just before the onset of spawning, increased with dorsal mantle length (L), where EP = 29.8L. For the average female squid (L of 129 mm), EP was 3844 oocytes. During the spawning period, no oogonia were produced; therefore the standing stock of oocytes declined as they were ovulated. This decline in oocytes was correlated with a decline in mantle condition and an increase in the size of the smallest oocyte in the ovary. Close agreement between the decline in estimated body weight and standing stock of oocytes during the spawning period indicated that maturation and spawning of eggs could largely, if not entirely, be supported by the conversion of energy reserves in tissue. Loligo opalescens, newly recruited to the spawning population, ovulated about 36% of their potential fecundity during their first spawning day and fewer ova were released in subsequent days. Loligo opalescens do not spawn all of their oocytes; a small percentage of the spawning population may live long enough to spawn 78% of their potential fecundity. Loligo opalescens are taken in a spawning grounds fishery off California, where nearly all of the catch are mature spawning adults. Thirty-three percent of the potential fecundity of L. opalescens was deposited before they were taken by the fishery (December 1998−99). This observation led to the development of a management strategy based on monitoring the escapement of eggs from the fishery. The strategy requires estimation of the fecundity realized by the average squid in the population which is a function of egg deposition and mortality rates. A model indicated that the daily total mortality rate on the spawning ground may be about 0.45 and that the average adult may live only 1.67 days after spawning begins. The rate at which eggs escape the fishery was modeled and the sensitivity of changing daily rates of fishing mortality, natural mortality, and egg deposition was examined. A rapid method for monitoring the fecundity of the L. opalescens catch was developed

Distributions and abundances of Pacific sardine (Sardinops sagax) and other pelagic fishes in the California Current Ecosystem during spring 2006, 2008, and 2010, estimated from acoustic–trawl surveys

The abundances and distributions of coastal pelagic fish species in the California Current Ecosystem from San Diego to southern Vancouver Island, were estimated from combined acoustic and trawl surveys conducted in the spring of 2006, 2008, and 2010. Pacific sardine (Sardinops sagax), jack mackerel (Trachurus symmetricus), and Pacific mackerel (Scomber japonicus) were the dominant coastal pelagic fish species, in that order. Northern anchovy (Engraulis mordax) and Pacific herring (Clupea pallasii) were sampled only sporadically and therefore estimates for these species were unreliable. The estimates of sardine biomass compared well with those of the annual assessments and confirmed a declining trajectory of the “northern stock” since 2006. During the sampling period, the biomass of jack mackerel was stable or increasing, and that of Pacific mackerel was low and variable. The uncertainties in these estimates are mostly the result of spatial patchiness which increased from sardine to mackerels to anchovy and herring. Future surveys of coastal pelagic fish species in the California Current Ecosystem should benefit from adaptive sampling based on modeled habitat; increased echosounder and trawl sampling, particularly for the most patchy and nearshore species; and directed-trawl sampling for improved species identification and estimations of their acoustic target stre

Prediction and confirmation of seasonal migration of Pacific sardine (Sardinops sagax) in the California Current Ecosystem

During the last century, the population of Pacific sardine (Sardinops sagax) in the California Current Ecosystem has exhibited large fluctuations in abundance and migration behavior. From approximately 1900 to 1940, the abundance of sardine reached 3.6 million metric tons and the “northern stock” migrated from offshore of California in the spring to the coastal areas near Oregon, Washington, and Vancouver Island in the summer. In the 1940s, the sardine stock collapsed and the few remaining sardine schools concentrated in the coastal region off southern California, year-round, for the next 50 years. The stock gradually recovered in the late 1980s and resumed its seasonal migration between regions off southern California and Canada. Recently, a model was developed which predicts the potential habitat for the northern stock of Pacific sardine and its seasonal dynamics. The habitat predictions were successfully validated using data from sardine surveys using the daily egg production method; scientific trawl surveys off the Columbia River mouth; and commercial sardine landings off Oregon, Washington, and Vancouver Island. Here, the predictions of the potential habitat and seasonal migration of the northern stock of sardine are validated using data from “acoustic–trawl” surveys of the entire west coast of the United States during the spring and summer of 2008. The estimates of sardine biomass and lengths from the two surveys are not significantly different between spring and summer, indicating that they are representative of the entire stock. The results also confirm that the model of potential sardine habitat can be used to optimally apply survey effort and thus minimize random and systematic sampling error in the biomass estimates. Furthermore, the acoustic–trawl survey data are useful to estimate concurrently the distributions and abundances of other pelagic fishes

A standardized terminology for describing reproductive development in fishes

19 páginas, 12 figuras, 3 tablas.-- Open access journalAs the number of fish reproduction studies has proliferated, so has the number of gonadal classification schemes and terms. This has made it difficult for both scientists and resource managers to communicate and for comparisons to be made among studies.We propose the adoption of a simple, universal terminology for the phases in the reproductive cycle, which can be applied to all male and female elasmobranch and teleost fishes. These phases were chosen because they define key milestones in the reproductive cycle; the phases include immature, developing, spawning capable, regressing, and regenerating. Although the temporal sequence of events during gamete development in each phase may vary among species, each phase has specific histological and physiological markers and is conceptually universal. The immature phase can occur only once. The developing phase signals entry into the gonadotropin-dependent stage of oogenesis and spermatogenesis and ultimately results in gonadal growth. The spawning capable phase includes (1) those fish with gamete development that is sufficiently advanced to allow for spawning within the current reproductive cycle and (2) batch-spawning females that show signs of previous spawns (i.e., postovulatory follicle complex) and that are also capable of additional spawns during the current cycle. Within the spawning capable phase, an actively spawning subphase is defined that corresponds to hydration and ovulation in females and spermiation in males. The regressing phase indicates completion of the reproductive cycle and, for many fish, completion of the spawning season. Fish in the regenerating phase are sexually mature but reproductively inactive. Species-specific histological criteria or classes can be incorporated within each of the universal phases, allowing for more specific divisions (subphases) while preserving the overall reproductive terminology for comparative purposes. This terminology can easily be modified for fishes with alternate reproductive strategies, such as hermaphrodites (addition of a transition phase) and livebearers (addition of a gestation phase)Fish Reproduction and Fisheries (FRESH; European Cooperation in Science and Technology Action FA0601) and theWest Palm Beach Fishing Club (Florida) provided funding for the gonadal histology workshops where this terminology was developed and refined. Additionally, we thank FRESH for travel and publication fundsPeer reviewe

An improved and simplified terminology for reproductive classification in fishes

As the number of fish reproductive studies has proliferated, so has the number of gonadal classification schemes and terms. This has made it difficult for managers and scientists to communicate and for comparisons to be made between studies. We propose the adoption of a simple, universal terminology for the phases in the reproductive cycle that can be used with all male and female elasmobranch and teleost fishes. These phases were chosen because they define key milestones in the reproductive cycle representing critical parameters such as size at maturity, duration of spawning season, location and diel periodicity of spawning, and fecundity. The phases we propose include: Immature, Developing, Spawning Capable, Actively Spawning, Regressing and Regenerating. Although the histological criteria identifying each phase may vary for different species and phases may not always occur sequentially, each phase is conceptually universal. The Immature phase can only occur once. The Developing phase signals entry into the gonadotropindependent stage of oogenesis and spermatogenesis and gonadal growth. The Spawning Capable phase indicates fish that will spawn this season because development within ovaries (fully grown vitellogenic oocytes) or testes (spermatozoa in lumens/ducts) is sufficiently advanced. Actively Spawning females are those that show recent evidence of spawning (i.e., hydrated or ovulated oocytes). Females of many species cycle between the Spawning Capable and Actively Spawning phases during the reproductive season and these phases are necessary to determine fecundity, spawning frequency, location and diel periodicity. Spawning Capable and Actively Spawning phases are difficult to differentiate histologically in males. The Regressing phase indicates fish that are completing the spawning season. Fish in the Regenerating phase are sexually mature but reproductively inactive. We show how researchers can incorporate species-specific histological criteria or classes within each of the universal phases, allowing more specific divisions yet preserving the overall reproductive terminology for comparative purposes

2010b. Spawning biomass of Pacific sardine (Sardinops sagax) off California in 2010

using the daily egg production method (DEPM) calculated by two methods: 1) the traditional method where the egg production (P0) was a weighted mean while each adult parameter was an unstratified estimate, and 2) a stratified procedure where the estimate of total spawning biomass is the sum of the estimated spawning biomass in each of two regions representing high and low spawning activity. Thus the two estimates of the spawning biomass were 383,286 mt (CV = 0.32) and 373,348 mt (CV = 0.28) respectively for the standard DEPM survey area of 314,480.69 km 2 off the west coast of North America from San Diego, California to north of San Francisco, California (CalCOFI line 60.0). The daily egg production estimate (P0, a weighted average with area as the weight) was 1.16/.05m 2 (CV = 0.26). In the standard DEPM area, the estimates of female spawning biomass calculated by the two methods were 225,155 mt (CV = 0.32) and 219,386 mt (CV = 0.28). Even though a small area close to Astoria, Oregon (47.1 °-45.9°N) was sampled, no eggs and only 2 immature sardine were collected in this area north of CalCOFI line 62.2. Hence, coastwide estimates of sardine spawning biomass and female spawning biomass were not calculated. The estimated daily specific fecundity was 19.04 (number of eggs/population weigh

A standardized terminology for describing reproductive development in fishes

6 páginas, 2 figurasPeer reviewe

ASSESSMENT OF THE PACIFIC SARDINE RESOURCE IN 2011 FOR U.S. MANAGEMENT IN 2012

Disclaimer: This information is distributed solely for the purpose of pre-dissemination peer review under applicable information quality guidelines. It has not been formally disseminated by NOAA-National Marine Fisheries Service. It does not represent and should not be construed to represent any agency determination or policy