Variable Oceanographic Conditions Research Articles

The key role of the Northern Mozambique Channel for Indian Ocean tropical tuna fisheries

The Northern Mozambique Channel (NMC) is a tropical area of ~ 1 million km2 where pelagic fisheries supply proteins to more than 9 million people living in Comoros, Mayotte, and along the coasts of Mozambique, Tanzania and Madagascar. Although uncertain, statistics suggest that about 20,000 mt of tropical tuna and other pelagic fish are annually caught by artisanal fisheries in the area. The NMC is also a major seasonal fishing ground for high-seas fleets that export an annual average catch of more than 20,000 mt to tuna can and sashimi markets of high-income countries for a value estimated to be more than 100 million USD. The fisheries productivity of the NMC appears to be highly variable in relation to strong annual and seasonal variability in oceanographic conditions. Our review shows that the NMC is a key feeding area for tropical tunas and a major spawning area for skipjack tuna thanks to warm waters and strong mesoscale activity that results in the enrichment of surface waters and efficient energy transfers enabled by short food chains. Projections of climate models under future warming scenarios predict some strong changes in the oceanographic conditions of the NMC which has already experienced substantial warming over the last decades. Changes in the pelagic ecosystem of the NMC could have dramatic consequences on the coastal populations that are expected to increase towards 100 million people by 2100. Improving monitoring systems and collecting information on the socio-economics of coastal fisheries is crucial to assess the dependence of NMC populations on tuna resources and empower the countries to more involvement in the management of tuna stocks.

Year-round tracking reveals multiple migratory tactics in a sentinel North Pacific seabird, Cassin’s auklet

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 619:169-185 (2019) - DOI: https://doi.org/10.3354/meps12965 Year-round tracking reveals multiple migratory tactics in a sentinel North Pacific seabird, Cassin’s auklet Katharine R. Studholme1,*, J. Mark Hipfner2, Alice D. Domalik3, Sara J. Iverson1, Glenn T. Crossin1 1Department of Biology, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada 2Environment and Climate Change Canada, Wildlife Research Division, Delta, British Columbia V4K 3N2, Canada 3Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada *Corresponding author: krstudholme@dal.ca ABSTRACT: Nonbreeding distributions and migratory phenology can vary within and among populations of many taxa, including seabirds. Such differences can drive variation in survival and reproduction. Knowledge of where, when, and why individuals move is therefore crucial to understanding and predicting population-level processes, particularly in the context of oceanographic change. Here we present the first year-round tracking data for Cassin’s auklet Ptychoramphus aleuticus, a small, zooplanktivorous North Pacific seabird, revealing the nonbreeding behavior of birds from colonies in British Columbia, Canada, across 3 years of variable oceanographic conditions. These birds moved both north (summer, fall) and south (fall, winter) from the colony, using 1 of 4 migratory tactics: North, South, North-South, or Local. Distributions ranged from the Aleutian Islands to Baja California, to maximum distances of 2757 and 3110 km, respectively. Within tactics there was additional spatiotemporal variation among individuals, resulting in diverse nonbreeding experiences. Some variability was explained by year and sex. Cassin’s auklets appear to target distinct, ecologically differentiated areas within their nonbreeding range which may have good quality habitat. Variation in these target regions across years suggests somewhat flexible migratory behavior; however, consistent migration to the Southern California Bight despite very low productivity in one study year suggests that fixed tactics may exist. This work contributes to our understanding of predator movement in the North Pacific and highlights the importance of individual-level spatial data for studies of carryover effects and conservation planning. KEY WORDS: Ptychoramphus aleuticus · Nonbreeding distribution · Migratory strategy · Partial migration · Individual variability · Geolocator · Alcidae · Marine heatwave · ‘The Blob’ · Mortality event Full text in pdf format Supplementary material PreviousNextCite this article as: Studholme KR, Hipfner JM, Domalik AD, Iverson SJ, Crossin GT (2019) Year-round tracking reveals multiple migratory tactics in a sentinel North Pacific seabird, Cassin’s auklet. Mar Ecol Prog Ser 619:169-185. https://doi.org/10.3354/meps12965 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 619. Online publication date: June 04, 2019 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2019 Inter-Research.

Effect of Azimuthal Asymmetry Caused by Upwelling on 3D Ocean Acoustic Propagation

3-D underwater parabolic equation model based on implicit finite difference method has been implemented for South Eastern Arabian Sea (SEAS). The bathymetric and geo-acoustic features have been integrated in the model for a 50 km circular region in SEAS. The model can simulate the effects of azimuthal variation in oceanographic features and compute azimuthally coupled pressure due to an omni-directional source. The azimuthal variation in oceanographic conditions can be observed during an upwelling event. In the first case study, the effect of upwelling event on three-dimensional acoustic propagation has been studied by using sound speed profile data derived from INS Sagardhwani observations. The difference in Transmission loss mosaic for upslope and downslope propagation is due to bathymetry as well as upwelling. In the second case study, the effect of upwelling only, is studied by running a model corresponding to range independent sound speed profile field and range dependent bathymetry. It was observed that during this upwelling event, the transmission loss is higher at longer ranges during upslope propagation than downslope propagation. This is due to the increase in the thickness of sonic layer duct as acoustic wave propagates from shallow to deep water. The effect of azimuthal variation i

Trophic ecology of European hake (Merlucius merlucius) larvae by stable isotopes analysis influenced by seasonal variability of oceanographic conditions off NW Galician waters.

Trophic ecology of European hake (Merlucius merlucius) larvae by stable isotopes analysis influenced by seasonal variability of oceanographic conditions off NW Galician waters.

Seasonal Variations in Marine Hydrological Characteristics off the Southwestern Coast of Sakhalin Island

Data of long-term observations at three standard oceanographic sections are analyzed. A complex pattern of seasonal variability of oceanographic conditions off the southwestern coast of Sakhalin Island is studied. It is shown that the cold West Sakhalin Current directed to the south is observed from May to October; the low-salinity cold flow of the Sea of Okhotsk water oriented to the north is recorded from November to March. The northern boundary of penetration of the Sea of Okhotsk water is identified.

Habitat use and movement patterns of small (age‐0) juvenile Pacific bluefin tuna (Thunnus orientalis) relative to the Kuroshio

AbstractThe habitat use of Pacific bluefin tuna (Thunnus orientalis; PBF) in nursery waters off the southern coast of Japan was investigated using archival tags over a 3 year study period (2012–2015), and the data were used to examine the free‐ranging habitat preferences of PBF and the relationship between their horizontal movements and the path of the Kuroshio off the Pacific coast of Japan. The path of the Kuroshio fluctuated seasonally, leading to changes in water temperature that strongly influenced the habitat use of small PBF (2–3 months after hatching). Most PBF were present in coastal waters inshore of the path of the current, and their habitat use changed in response to the distance of the current from the coast. The Kuroshio typically flowed along the coast from summer to autumn, and PBF remained in the coastal waters off Kochi Prefecture during this period. In contrast, PBF quickly moved eastward in winter when the current moved away from the coast. Throughout the winter and spring, the area of habitat use extended widely from the eastern end of the southern coast of Japan (the Boso Peninsula) to the offshore Kuroshio‐Oyashio transition region. These findings suggest that the seasonal habitat use and movement behavior of juvenile PBF are influenced by the distance of the Kuroshio axis from the coast, and the ultimate drivers are likely variations in oceanographic conditions and prey availability along the southern coast of Japan.

Spatiotemporal variations in life-history traits and statolith trace elements of Sepioteuthis lessoniana populations around northern Taiwan

The bigfin reef squid Sepioteuthis lessoniana is a neritic species widely distributed in coastal waters of the Indo-Pacific region and is of interest to fisheries for its high commercial value. Squid samples were collected from Keelung (KL) and Penghu (PH), around northern Taiwan from October 2012 to September 2013. A total of 949 squid were examined, and 620 squid were aged using statoliths. The age range of the squid in KL (55–183 days) was similar to that in PH (77–186 days). The squid hatched almost year-round, except in January and December in KL. Two seasonal cohorts were identified: a spring cohort (hatched in March to May) and an autumn cohort (July to October). Concentrations of nine trace elements in statoliths were analysed using solution-based inductively coupled plasma mass spectrometry (ICP-MS). Significant differences in Fe/Ca, Cu/Ca and Sr/Ca were found between the two locations, while significant differences in concentration ratios of Sr/Ca and Ba/Ca were noted between the two seasonal cohorts. Results of a principal component analysis and cluster analysis varied in life-history traits between the two geographic stocks and in elemental concentrations between the two seasonal cohorts. Squid in KL and PH might undertake different migration routes, while seasonal variability in oceanographic conditions was apparent in the two locations.

Front‐Eddy Influence on Water Column Properties, Phytoplankton Community Structure, and Cross‐Shelf Exchange of Diatom Taxa in the Shelf‐Slope Area off Concepción (∼36–37°S)

AbstractIn eastern boundary current systems (EBCSs), submesoscale to mesocale variability contributes to cross‐shore exchanges of water properties, nutrients, and plankton. Data from a short‐term summer survey and satellite time series (January–February 2014) were used to characterize submesoscale variability in oceanographic conditions and phytoplankton distribution across the coastal upwelling and coastal transition zones north of Punta Lavapié, and to explore cross‐shelf exchanges of diatom taxa. A thermohaline front (FRN‐1) flanked by a mesoscale anticyclonic intrathermocline eddy (ITE‐1), or mode‐water eddy, persisted during the time series and the survey was undertaken during a wind relaxation event. At the survey time, ITE‐1 contributed to an onshore intrusion of warm oceanic waters (southern section) and an offshore advection of cold coastal waters (northern section), with the latter forming a cold, high chlorophyll‐a filament. In situ phytoplankton and diatom biomasses were highest at the surface in FRN‐1 and at the subsurface in ITE‐1, whereas values in the coastal zone were lower and dominated by smaller cells. Diatom species typical of the coastal zone and species dominant in oceanic waters were both found in the FRN‐1 and ITE‐1 interaction area, suggesting that this mixture was the result of both offshore and onshore advection. Overall, front‐eddy interactions in EBCSs could enhance cross‐shelf exchanges of coastal and oceanic plankton, as well as sustain phytoplankton growth in the slope area through localized upward injections of nutrients in the frontal zone, combined with ITE‐induced advection and vertical nutrient inputs to the surface layer.

Validation of a hidden Markov model for the geolocation of Atlantic cod

Models developed to geolocate individual fish from data recorded by electronic tags often require major modification to be applied to new regions, species, or tag types due to variability in oceanographic conditions, fish behavior, and data resolution. We developed a model for geolocating Atlantic cod (Gadus morhua) off New England that builds upon an existing hidden Markov model (HMM) framework and addresses region- and species-specific challenges. The HMM framework contains a likelihood model that compares tag-recorded environmental data (depth, temperature, tidal characteristics) with those derived from an oceanographic model and a behavior model that constrains the horizontal movement of the fish. Validation experiments were performed on stationary tags, double-electronic-tagged fish (archival and acoustic tags), and simulated tracks. Known data, including fish locations and activity metrics, showed good agreement with those estimated by the modified approach and improvements in performance of the modified method over the original. The modified geolocation approach will be applicable to additional species and regions to obtain valuable movement information that is not typically available for demersal fishes.

Putting all the pieces together: integrating current knowledge of the biology, ecology, fisheries status, stock structure and management of yellowfin tuna (Thunnus albacares)

Yellowfin tuna (Thunnus albacares; YFT) is an apex marine predator inhabiting tropical and sub-tropical pelagic waters. It supports the second largest tuna fishery in the world. Here, we review the available literature on YFT to provide a detailed overview of the current knowledge of its biology, ecology, fisheries status, stock structure and management, at global scale. YFT are characterized by several peculiar anatomical and physiological traits that allow them to survive in the oligotrophic waters of the pelagic realm. They are opportunistic feeders, which allows fast growth and high reproductive outputs. Globally, YFT fisheries have expanded over the last century, progressively moving from coastal areas into the majority of sub-tropical and tropical waters. This expansion has led to a rapid increase in global commercial landings, which are predominantly harvested by industrial longline and purse seine fleets. For management purposes, YFT is divided into four stocks, each of which is currently managed by a separate tuna Regional Fisheries Management Organization. Our current understanding of YFT stock structure is, however, still uncertain, with conflicting evidence arising from genetic and tagging studies. There is, moreover, little information about their complex life-history traits or the interactions of YFT populations with spatio-temporally variable oceanographic conditions currently considered in stock assessments. What information is available, is often conflicting at the global scale. Finally, we suggest future research directions to manage this valuable resource with more biological realism and more sustainable procedures.

Diel vertical migration and cross-shore distribution of barnacle and bivalve larvae in the central Chile inner-shelf

The vertical and horizontal distribution of larval stages of the most common intertidal barnacle and mussel species were characterized in near-shore waters of central Chile. Paired day/night cruises were conducted on four spring-summer dates between December 2007 and November 2008, under contrasting wind, wave height, and near-shore stratification conditions. Regardless of variability in oceanographic conditions, the highest abundances of barnacle and mussel larvae were found within 1500m from shore. Non-uniform vertical distributions were observed for chthamalids, balanids and mussel larvae, but patterns of diel variability differed among them. Chthamalid and balanid nauplii, as well as balanid cyprids were more abundant in the upper 20m of the water column, while the density of chthamalid cyprids was highest near the bottom. Mussel larvae were only found within 20m of the surface. The Mean Depth Distribution (MDD) of all nauplii (balanid and chthamalid) and chthamalid cyprids was deeper during day than night, suggesting typical diel vertical migration (DVM), but this difference was statistically significant only for nauplii. Mussels did not show diel differences in vertical distribution. The amplitude of DVM, measured as the difference between daytime and nighttime MDD, decreased with increasing wave height in chthamalid and balanid nauplii, but not with along-shore wind stress. Chthamalid nauplii, and to a lesser extent, balanid nauplii were found below the pycnocline during the day and above at night, suggesting that DVM involves daily crossing of this density barrier. In contrast, cyprids of all barnacle species were distributed across the pycnocline with no clear pattern. The results suggest that barnacle and bivalve larvae may exhibit a variety of behavioral responses to position themselves in the water column despite typically turbulent near-shore waters, and that such behavior varies between species and through ontogeny within species. Moreover, some stages of barnacle larvae perform DVM, but the amplitude decreased with increasing wave height – which may be either a plastic response to environmental cues or merely turbulent mixing impeding the ability of larvae to perform vertical migration.

Seasonal changes in fish assemblage structure at a shallow seamount in the Gulf of California.

Seamounts have generally been identified as locations that can promote elevated productivity, biomass and predator biodiversity. These properties attract seamount-associated fisheries where elevated harvests can be obtained relative to surrounding areas. There exists large variation in the geological and oceanographic environment among the thousands of locations that fall within the broad definition of seamount. Global seamount surveys have revealed that not all seamounts are hotspots of biodiversity, and there remains a strong need to understand the mechanisms that underlie variation in species richness observed. We examined the process of fish species assembly at El Bajo Espiritu Santo (EBES) seamount in the Gulf of California over a five-year study period. To effectively quantify the relative abundance of fast-moving and schooling fishes in a ‘blue water’ habitat, we developed a simplified underwater visual census (UVC) methodology and analysis framework suitable for this setting and applicable to future studies in similar environments. We found correlations between seasonally changing community structure and variability in oceanographic conditions. Individual species responses to thermal habitat at EBES revealed three distinct assemblages, a ‘fall assemblage’ tracking warmer overall temperature, a ‘spring assemblage’ correlated with cooler temperature, and a ‘year-round assemblage’ with no significant response to temperature. Species richness was greatest in spring, when cool and warm water masses stratified the water column and a greater number of species from all three assemblages co-occurred. We discuss our findings in the context of potential mechanisms that could account for predator biodiversity at shallow seamounts.

Sedimentary patterns and palaeoceanography of the Albian Marne a Fucoidi Formation (Central Italy) revealed by high‐resolution geochemical and nannofossil data

AbstractThe pelagic Marne a Fucoidi Formation from the Umbria–Marche Basin (Central Italy) is one of the best‐preserved deep‐marine archives of the Aptian–Albian. Frequent changes in lithology, from black to green and red marlstones and limestones, record fluctuating oceanographic and climatic conditions during the deposition of these sediments. Here, the lithological changes in the Albian of the Marne a Fucoidi Formation are studied with unprecedented resolution using X‐ray fluorescence core scanning measurements of major and minor element abundances, as well as statistical analyses of calcareous nannofossil indices. The results obtained with these two independent methodologies are in good agreement and allow for improving the understanding of the peculiar palaeoceanographic conditions of the western Tethys during the Albian. Black shale–marlstone couplets were driven by orbitally forced changes in physical oceanography, resulting in oxygen‐depleted bottom water at times of decreased mixing of shallow water masses. On the other hand, red marlstones represent episodes of enhanced oxygenation at the bottom, probably due to the influence of deep waters from the eastern Tethys. Overall, the Marne a Fucoidi Formation is the expression of highly variable oceanographic conditions related to an unstable Albian circulation mode.

Repetitive harvesting of Macrocystis pyrifera (Phaeophyceae) and its effects on chemical constituents of economic value

Abstract Kelp harvesting has increased globally in recent decades and is expected to continue rising as the demand for kelp-derived products for use in aquaculture and industrial applications increases. In response, numerous studies have examined how harvesting impacts kelp populations and their associated communities, but the effects of repeated harvesting of the same individuals on the chemical properties for which they are extracted remain poorly understood. This knowledge gap may be especially crucial in areas where the same kelps are necessarily harvested multiple times per year due to their overall low abundance. To address this, we examined how repetitive harvesting of the same individuals of giant kelp, Macrocystis pyrifera, over a 3-month period influences tissue chemical properties (i.e. alginate yield, viscosity and strength, nutritional quality, such as protein, carbohydrate, lipid, crude fiber, ash and energy content, and tissue carbon/nitrogen ratios). Our results indicate that, while these properties vary over time, presumably due to variability in oceanographic conditions, repetitive harvesting of the same individuals does not significantly impact these properties.

Two-element acoustic array gives insight into ice-ocean interactions in Hornsund Fjord, Spitsbergen

AbstractGlacierized fjords are dynamic regions, with variable oceanographic conditions and complex ice-ocean interactions, which are still poorly understood. Recent studies have shown that passive underwater acoustics offers new promising tools in this branch of polar research. Here, we present results from two field campaigns, conducted in summer 2013 and spring 2014. Several recordings with a bespoke two-hydrophone acoustic buoy were made in different parts of Hornsund Fjord, Spitsbergen in the vicinity of tidewater glaciers to study the directionality of underwater ambient noise. Representative segments of the data are used to illustrate the analyses, and determine the directions of sound sources by using the time differences of arrivals between two horizontally aligned, broadband hydrophones. The results reveal that low frequency noise (< 3 kHz) is radiated mostly from the ice cliffs, while high-frequency (> 3 kHz) noise directionality strongly depends on the distribution of floating glacial ice throughout the fjord. Changing rates of iceberg production as seen for example in field photographs and logs are, in turn, most likely linked to signal amplitudes for relevant directions. These findings demonstrate the potential offered by passive acoustics to study the dynamics of individual tidewater glaciers.

Distribución y abundancia de Oncaea venusta y O. media (Crustacea: Copepoda) en el Pacífico colombiano durante dos periodos en 2001

Zooplankton of the Colombian Pacific Ocean was investigated during June-July (2001a) and August-September (2001b). Since Oncaea venusta and O. media predominated in the copepod community, their distribution and abundance were evaluated. Organisms were extracted from surface mesozooplankton samples taken with a conic net (50cm opening, 363 μ m mesh). Both species were widely distributed with highest abundances mainly in neritic waters (3°-5°N). Factor analysis revealed negative and positive correlations among abundances and abiotic variables depending on each period. Cluster analysis showed three groups in 2001a and five ones in 2001b, essentially consistent with night and day abundances, and thermocline depth and width suggesting the influence of these factors on O. venusta and O. media . In future analysis it may be necessary to consider the different forms of O. media and O. venusta to establish the importance of phytoplankton and other organisms in their diet. Higher night or day abundances allude to the possible diel vertical migration of these microcrustaceans to the surface. The decrease in the general abundance of O. venusta from 2001a to 2001b (66.4% to 47.5%) contrasted with the increase of O. media (33.6% to 52.5%). These changes could be explained by the different biological response of both species to short-term variability in oceanographic conditions and the occurrence of a weak La Nina event.

An individual-based model of the krill Euphausia pacifica in the California Current

Euphausia pacifica is an abundant and important prey resource for numerous predators of the California Current and elsewhere in the North Pacific. We developed an individual-based model (IBM) for E. pacifica to study its bioenergetics (growth, stage development, reproduction, and mortality) under constant/ideal conditions as well as under varying ocean conditions and food resources. To model E. pacifica under varying conditions, we coupled the IBM to an oceanographic-ecosystem model over the period 2000–2008 (9years). Model results under constant/ideal food conditions compare favorably with experimental studies conducted under food unlimited conditions. Under more realistic variable oceanographic conditions, mean growth rates over the continental shelf were positive only when individuals migrated diurnally to the depth of maximum phytoplankton layer during nighttime feeding. Our model only used phytoplankton as prey and coastal growth rates were lower than expected (0.01mmd−1), suggesting that a diverse prey base (zooplankton, protists, marine snow) may be required to facilitate growth and survival of modeled E. pacifica in the coastal environment. This coupled IBM–ROMS modeling framework and its parameters provides a tool for understanding the biology and ecology of E. pacifica and could be developed to further the understanding of climatic effects on this key prey species and enhance an ecosystem approach to fisheries and wildlife management in this region.

Synchrony and variation across latitudinal gradients: The role of climate and oceanographic processes in the growth of a herbivorous fish

Spatial and temporal variation in the growth of a widely distributed temperate marine herbivore, Girella elevata, was examined using length-at-age data and multi-decadal otolith increment growth chronologies. In total 927 G. elevata were collected from three regions of the Australian south-east coast, extending 780km and covering the majority of the East Australian Current, a poleward-flowing western boundary current of the Southern Pacific Gyre and climate change hotspot. A validated ageing method using sectioned sagittal otoliths was developed to enumerate both daily (juvenile fish) and annual otolith increments. G. elevata exhibited great longevity with a maximum recorded age of 45+yrs. Spatial variation in growth from length-at-age data was observed with the highest growth rates within the centre of the species distribution. Analysis of otolith growth chronologies of 33yrs showed a positive relationship with the Southern Oscillation Index. Identifying links between life-history characteristics and variation in oceanographic conditions across latitudinal gradients may shed light on potential impacts of expected climate shifts on fish productivity.

Salmon ocean migration models suggest a variety of population-specific strategies

Many species of salmon around the world migrate to open ocean environments for multiple years and then return to their natal rivers to spawn. How exactly salmon are able to execute these long distance migrations, and the impact of environmental conditions on migration behavior, is not well understood. Individual based modeling is one tool that has been used to explore salmon migration in the ocean. Although models are usually not able to confirm whether a particular behavior is used, they can rule out some behaviors as unrealistic. An extensive review of published literature suggests that there is no universal migration behavior. Behaviors that fish use to navigate depend on where they are in the ocean relative to where they are going, as well as the ocean flows and conditions along the way. Future models of salmon migration should be flexible and at an appropriate scale to capture variable oceanographic conditions and fish responses.

Variability in rockfish (Sebastes spp.) fecundity: species contrasts, maternal size effects, and spatial differences

Over 60 species of rockfish (Sebastes spp.) reside off the coast of California, many of which are economically important to both recreational and com- mercial fisheries. Rockfish are live-bearers with a di- verse array of reproductive strategies. Understanding thereproductivepotentialofanexploitedstockiscritical to assessing the health and status of a fishery. We inves- tigated the reproductive ecology offour 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 posi- tively correlated with relative fecundity (larvae per g somatic weight) in all four species, indicating a dispro- portionately greater reproductive output by larger, older females. Fecundity estimates in Chilipepper, S. goodei, and Yellowtail rockfish, S. flavidus ,v aried regionally, but did not significantlydiffer overtimewithinthe years sampled (sample sizes for Speckled, S. ovalis ,a nd 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 re- gions multiple broods were common, complicating es- timates of annual fecundity for these two species. There was some evidence that egg production was positively correlated with female condition, indicating that envi- ronmental variability in oceanographic conditions and productivity may drive changes in fecundity and repro- ductive strategy (i.e., single versus multiple broods).