Search results | Digital Commons of Moss Landing Marine Laboratories

Title: Development of New Methods for Quantifying Fish Density Using Underwater Stereo-video Tools
Description: The use of video camera systems in ecological studies of fish continues to gain traction as a viable, non-extractive method of measuring fish lengths and estimating fish abundance. We developed and implemented a rotating stereo-video camera tool that covers a full 360 degrees of sampling, which maximizes sampling effort compared to stationary camera tools. A variety of studies have detailed the ability of static, stereo-camera systems to obtain highly accurate and precise measurements of fish; the focus here was on the development of methodological approaches to quantify fish density using rotating camera systems. The first approach was to develop a modification of the metric MaxN, which typically is a conservative count of the minimum number of fish observed on a given camera survey. We redefine MaxN to be the maximum number of fish observed in any given rotation of the camera system. When precautions are taken to avoid double counting, this method for MaxN may more accurately reflect true abundance than that obtained from a fixed camera. Secondly, because stereo-video allows fish to be mapped in three-dimensional space, precise estimates of the distance-from-camera can be obtained for each fish. By using the 95% percentile of the observed distance from camera to establish species-specific areas surveyed, we account for differences in detectability among species while avoiding diluting density estimates by using the maximum distance a species was observed. Accounting for this range of detectability is critical to accurately estimate fish abundances. This methodology will facilitate the integration of rotating stereo-video tools in both applied science and management contexts.
Author: Denney, Fields, Gleason, Starr

Title: Movements of small adult black rockfish: Implications for the design of MPAs
Description: Off the coast of central California, USA, small black rockfish Sebastes melanops (individuals below the length at 50% maturity) comprise a large percentage of the catch in recreational fisheries, yet little is known about the movements of these small fish. To better understand their movements, we implanted acoustic transmitters into 23 black rockfish (29 to 41 cm total length) in Carmel Bay, California, USA. Tagged fish were monitored over a 16 mo period between August 2006 and January 2008. Their vertical movements were correlated with environmental variables such as atmospheric pressure, wind speed, upwelling, and wave height. From October to May, black rockfish moved to deeper waters offshore during the day and returned at night. In the summer, diurnal movements of black rockfish decreased in frequency, perhaps due to locally abundant food resources associated with seasonal upwelling. About two-thirds of the tagged black rockfish (14 fish) displayed a high degree of residency to the study area (>11 mo). The remaining third (9 fish) left the study area within 6 mo of release; signals from 4 of these fish were later detected on other acoustic receiver arrays >50 km north of Carmel Bay. Storms may have caused those fish to move northward in winter. When in residence, the mean home range of tagged fish was 0.25 km2. Our results indicate that a better understanding of the variability of fish movements among age classes is necessary to design marine protected areas (MPAs) that are intended to protect all life stages of a species. © 2011 Inter-Research., Cited By (since 1996):2, CODEN: MESED
Author: Green, Starr
Date: 2011-01-01T00:00:00Z

Title: Habitat use, residency, and seasonal distribution of female leopard sharks Triakis semifasciata in Elkhorn Slough, California,
Description: Bays and estuaries play important roles in the life history of leopard sharks Triakis semifasciata, yet these coastal environments are among those most impacted by human activity. To better understand habitat use, spatial associations, and ecological roles of leopard sharks in estuarine environments, movements of leopard sharks were studied in Elkhorn Slough, California, USA. A total of 21 female leopard sharks (78 to 140 cm total length) were tagged with acoustic transmitters and tracked from August 2003 to February 2005. Eight sharks were manually tracked for 20 to 71.5 h, and 13 sharks were monitored for 4 to 280 d using an array of acoustic receivers. Female leopard sharks exhibited a high degree of fidelity to Elkhorn Slough. The distribution of tagged sharks changed seasonally and was likely associated with changes in temperature, salinity, and dissolved oxygen. Sharks used the area that comprises Elkhorn Slough National Estuarine Research Reserve (ESNERR) extensively throughout the year, but especially during spring and summer. When sharks occupied ESNERR, their habitat use was tidally influenced, with sharks using low intertidal mudflats extensively when available. Sharks using the main channel tended to remain in subtidal habitats at all tidal levels. These results suggest that efforts to protect important leopard shark habitats in bays and estuaries should focus on preserving and restoring intertidal mudflats., Cited By (since 1996):23, CODEN: MESED, ,
Author: Carlisle, Starr
Date: 2009-01-01T00:00:00Z

Title: Fitting state-space integral projection models to size-structured time series data to estimate unknown parameters
Description: Export Date: 24 October 2016, Article in Press
Author: White, Nickols, Malone, Carr, Starr, Cordoleani, Baskett, Hastings, Botsford
Date: 2016-01-01T00:00:00Z

Title: Thermal stratification drives movement of a coastal apex predator
Description: A characterization of the thermal ecology of fishes is needed to better understand changes in ecosystems and species distributions arising from global warming. The movement of wild animals during changing environmental conditions provides essential information to help predict the future thermal response of large marine predators. We used acoustic telemetry to monitor the vertical movement activity of the common dentex (Dentex dentex), a Mediterranean coastal predator, in relation to the oscillations of the seasonal thermocline during two summer periods in the Medes Islands marine reserve (NW Mediterranean Sea). During the summer stratification period, the common dentex presented a clear preference for the warm suprathermoclinal layer, and adjusted their vertical movements following the depth changes of the thermocline. The same preference was also observed during the night, when fish were less active. Due to this behaviour, we hypothesize that inter-annual thermal oscillations and the predicted lengthening of summer conditions will have a significant positive impact on the metabolic efficiency, activity levels, and population dynamics of this species, particularly in its northern limit of distribution. These changes in the dynamics of an ecosystem's keystone predator might cascade down to lower trophic levels, potentially re-defining the coastal fish communities of the future. © 2017 The Author(s).
Author: Aspillaga, Bartumeus, Starr, López-Sanz, Linares, DIáz, Garrabou, Zabala, Hereu

Title: Targeting Abundant Fish Stocks while Avoiding Overfished Species: Video and Fishing Surveys to Inform Management after Long-Term Fishery Closures
Description: Historically, it has been difficult to balance conservation goals and yield objectives when managing multispecies fisheries that include stocks with various vulnerabilities to fishing. As managers try to maximize yield in mixed-stock fisheries, exploitation rates can lead to less productive stocks becoming overfished. In the late 1990s, population declines of several U.S. West Coast groundfish species caused the U.S. Pacific Fishery Management Council to create coast-wide fishery closures, known as Rockfish Conservation Areas, to rebuild overfished species. The fishery closures and other management measures successfully reduced fishing mortality of these species, but constrained fishing opportunities on abundant stocks. Restrictive regulations also caused the unintended consequence of reducing fishery-dependent data available to assess population status of fished species. As stocks rebuild, managers are faced with the challenge of increasing fishing opportunities while minimizing fishing mortality on rebuilding species. We designed a camera system to evaluate fishes in coastal habitats and used experimental gear and fishing techniques paired with video surveys to determine if abundant species could be caught in rocky habitats with minimal catches of co-occurring rebuilding species. We fished a total of 58 days and completed 741 sets with vertical hook-and-line fishing gear. We also conducted 299 video surveys in the same locations where fishing occurred. Comparison of fishing and stereo-video surveys indicated that fishermen could fish with modified hook-and-line gear to catch abundant species while limiting bycatch of rebuilding species. As populations of overfished species continue to recover along the U.S. West Coast, it is important to improve data collection, and video and fishing surveys may be key to assessing species that occur in rocky habitats.
Author: Starr, Gleason, Marks, Kline, Rienecke, Denney, Tagini, Field

Title: Growth, mortality, and reproductive seasonality of California Halibut (Paralichthys californicus): A biogeographic approach
Description: Differences in key biological processes, such as growth and reproduction, can greatly influence localized population dynamics. Thus, it is important to characterize spatial variation in life history traits of harvested species to develop management plans that maximize fishery sustainability. We estimated sex- and region-specific growth, total mortality, and reproductive seasonality to assess biogeographic differences in California Halibut life history. We found that central California Halibut grew faster but attained smaller maximum sizes than those from southern California. Catch curve analysis illustrated no difference in total mortality by sex or region, though females live longer than males. Year-class frequency distributions suggested greater recruitment variability in central California, where abiotic factors (e.g., upwelling strength, sea surface temperature) are likely drivers. Reproductive data indicated that summer spawning seasons peak earliest in Mexico, followed by southern and central California. These results demonstrate a need to assess and manage California Halibut at the regional scale.
Author: Barnes, Starr, Reilly
Date: 2015-01-01T00:00:00Z

Title: Changes in size composition and relative abundance of fishes in Central California after a decade of spatial fishing closures
Description: Rockfish Conservation Areas (RCAs) were implemented in 2000 to 2003 along the West Coast of the United States to reduce fishing mortality on rockfish (Sebastes spp.) and other groundfish species that had recently been declared overfished. In 2012, we initiated a study to compare recent catch rates, species compositions and length frequencies of fishes inside and outside the RCAs with data collected in central California between 1995 and 1998. At all sites surveyed, total catch rates from the new surveys (2012–14) were significantly higher than catch rates from before RCA implementation (1995–98). The majority of the differences were due to the increased relative abundance of yellowtail rockfish (Sebastes flavidus), although other species, including the overfished canary rockfish (Sebastes pinniger), also increased. Differences in the size composition of species between the two time periods reflected both the increased survival of older fishes and higher recruitment success in the past decade. © 2015, Scripps Institution of Oceanography. All rights reserved., published
Author: Marks, Fields, Starr, Field, Miller, Beyer, Sogard, Wilson-Vandenberg, Howard

Title: Complementary sampling methods to inform ecosystem-based management of nearshore fisheries,
Description: Area-based fishery management and ecosystem-based management strategies are considered beneficial marine resource management tools, but they require finite information about the structure and function of ecosystems to evaluate populations and describe the effects of fishing on ecosystems. The required information is not likely to be obtained from sporadic, fishery-dependent data collected from data-poor fisheries, and funding constraints preclude extensive fishery-independent surveys. This situation has led to an interest in relating or combining information from a variety of disparate sampling methods. From 2003 to 2006, we investigated the relationships between estimates of catch per unit effort (CPUE) and the abundance of fishes generated from typical nearshore commercial fishing operations and estimates of density and abundance derived from scuba surveys in the same locations. The relationships between CPUE and the density estimates derived from different sampling methods were found to be statistically significant in the case of many of the common species sampled across sites in Carmel Bay, California. The compounding effects of within-sample variance and the error associated with the regression equations, however, would result in poor confidence in the values translated from one sampling method to another. Different sampling methods may provide reasonable estimates of population trends, but they are sufficiently different and variable as to preclude the use of a scaling factor to standardize population estimates among sampling methods. Also, the differences in species composition (i.e., relative CPUE or density among species) produced by each sampling method were significant and were also affected by habitat relief and sample depth. Nonetheless, our results suggest the value of a cost-benefit analysis that would allow managers to design optimal sampling strategies for characterizing CPUE relationships within a region of interest. A sampling program that benefits from the complementary strengths of fishing gear and scuba sampling will probably result in the most comprehensive description of nearshore fish assemblages. © American Fisheries Society 2010., Cited By (since 1996):3 Fish and Fisheries, ,
Author: Starr, Carr, Malone, Greenley, McMillan
Date: 2010-01-01T00:00:00Z

Title: Fitting state-space integral projection models to size-structured time series data to estimate unknown parameters
Description: Integral projection models (IPMs) have a number of advantages over matrix-model approaches for analyzing size-structured population dynamics, because the latter require parameter estimates for each age or stage transition. However, IPMs still require appropriate data. Typically they are parameterized using individual-scale relationships between body size and demographic rates, but these are not always available. We present an alternative approach for estimating demographic parameters from time series of size-structured survey data using a Bayesian state-space IPM (SSIPM). By fitting an IPM in a state-space framework, we estimate unknown parameters and explicitly account for process and measurement error in a dataset to estimate the underlying process model dynamics. We tested our method by fitting SSIPMs to simulated data; the model fit the simulated size distributions well and estimated unknown demographic parameters accurately. We then illustrated our method using nine years of annual surveys of the density and size distribution of two fish species (blue rockfish, Sebastes mystinus, and gopher rockfish, S. carnatus) at seven kelp forest sites in California. The SSIPM produced reasonable fits to the data, and estimated fishing rates for both species that were higher than our Bayesian prior estimates based on coast-wide stock assessment estimates of harvest. That improvement reinforces the value of being able to estimate demographic parameters from local-scale monitoring data. We highlight a number of key decision points in SSIPM development (e.g., open vs. closed demography, number of particles in the state-space filter) so that users can apply the method to their own datasets.
Author: White, Nickols, Malone, Carr, Starr, Cordoleani, Baskett, Hastings, Botsford
Institution: Ecological Society of America

Title: The structure of Mediterranean rocky reef ecosystems across environmental and human gradients, and conservation implications
Description: Historical exploitation of the Mediterranean Sea and the absence of rigorous baselines makes it difficult to evaluate the current health of the marine ecosystems and the efficacy of conservation actions at the ecosystem level. Here we establish the first current baseline and gradient of ecosystem structure of nearshore rocky reefs at the Mediterranean scale. We conducted underwater surveys in 14 marine protected areas and 18 open access sites across the Mediterranean, and across a 31-fold range of fish biomass (from 3.8 to 118 g m -2). Our data showed remarkable variation in the structure of rocky reef ecosystems. Multivariate analysis showed three alternative community states: (1) large fish biomass and reefs dominated by non-canopy algae, (2) lower fish biomass but abundant native algal canopies and suspension feeders, and (3) low fish biomass and extensive barrens, with areas covered by turf algae. Our results suggest that the healthiest shallow rocky reef ecosystems in the Mediterranean have both large fish and algal biomass. Protection level and primary production were the only variables significantly correlated to community biomass structure. Fish biomass was significantly larger in well-enforced no-take marine reserves, but there were no significant differences between multi-use marine protected areas (which allow some fishing) and open access areas at the regional scale. The gradients reported here represent a trajectory of degradation that can be used to assess the health of any similar habitat in the Mediterranean, and to evaluate the efficacy of marine protected areas., Cited By (since 1996):21, Art. No.: e32742
Author: Sala, Ballesteros, Dendrinos, Di Franco, Ferretti, Foley, Fraschetti, Friedlander, Garrabou, Güçlüsoy, Guidetti, Halpern, Hereu, Karamanlidis, Kizilkaya, Macpherson, Mangialajo, Mariani, Micheli, Pais, Riser, Rosenberg, Sales, Selkoe, Starr, Tomas, Zabala
Date: 2012-01-01T00:00:00Z

Title: Collaborative research: An effective way to collect data for stock assessments and evaluate marine protected areas in California,
Description: Collaborative fisheries research (in contrast to cooperative research) is based on the intellectual partnership between scientists and fishermen and is an effective way to collect data for stock assessments and to evaluate marine protected areas. Collaborative fisheries research is discussed in the context of comanagement of marine resources and how it contributes to a more democratic form of fisheries management. Many benefits result from working together, including (1) the incorporation of fishers' knowledge and expertise into the management process and (2) the development of shared perspectives derived through science-based investigations on the status of marine resources. The California Collaborative Fisheries Research Program was formed in 2006 to participate in the monitoring of marine reserves established through California's Marine Life Protection Act. This program has shown that it can serve as a model for other areas that are trying to implement collaborative research and that collaborative research can greatly contribute to the realization of community-based co-management of marine resources. © Copyright by the American Fisheries Society 2009., Cited By (since 1996):5 Fish and Fisheries, ,
Author: Wendt, Starr
Date: 2009-01-01T00:00:00Z

Title: Tidal movements of female leopard sharks (Triakis semifasciata) in Elkhorn Slough, California
Description: The leopard shark (Triakis semifasciata) is one of the most common species of elasmobranch in California, and uses the shallow bays and estuaries of California extensively throughout its life history. To examine the role that tides and time of day play on the distribution and movements of leopard sharks in an estuarine environment, a total of 22 female leopard sharks (78-140 cm TL) were tagged with acoustic transmitters in Elkhorn Slough, California, USA. Eight sharks were manually tracked for 20-71. 5 h, and 13 sharks were monitored for 4-280 days using an array of acoustic receivers. Overall, the distribution and movements of sharks were strongly influenced by the tides and to a lesser extent by period of day, although general patterns of movement differed depending on what region of Elkhorn Slough the sharks were using. In the main channel of Elkhorn Slough, sharks generally moved with the tide, maximizing the area over which they could forage on a more dispersed prey field. Conversely, leopard sharks within the Elkhorn Slough National Estuarine Research Reserve regularly swam against strong currents to remain in proximity to the intertidal mudflats. This high degree of fidelity to a specific region was probably due to an abundance of important prey in the area. These results indicate that movements, and thus the foraging ecology, of leopard sharks show a high degree of plasticity and are influenced by tidal stage, tidal current, availability of suitable habitat, and availability and distribution of important prey items. © 2010 Springer Science+Business Media B.V., Cited By (since 1996):2, Fish and Fisheries, CODEN: EBFID
Author: Carlisle, Starr
Date: 2010-01-01T00:00:00Z

Title: Ordinary and Extraordinary Movement Behaviour of Small Resident Fish within a Mediterranean Marine Protected Area
Description: It is important to account for the movement behaviour of fishes when designing effective marine protected areas (MPAs). Fish movements occur across different spatial and temporal scales and understanding the variety of movements is essential to make correct management decisions. This study describes in detail the movement patterns of an economically and commercially important species, Diplodus sargus, within a well-enforced Mediterranean MPA. We monitored horizontal and vertical movements of 41 adult individuals using passive acoustic telemetry for up to one year. We applied novel analysis and visualization techniques to get a comprehensive view of a wide range of movements. D. sargus individuals were highly territorial, moving within small home ranges (< 1 km2), inside which they displayed repetitive diel activity patterns. Extraordinary movements beyond the ordinary home range were observed under two specific conditions. First, during stormy events D. sargus presented a sheltering behaviour, moving to more protected places to avoid the disturbance. Second, during the spawning season they made excursions to deep areas (> 50 m), where they aggregated to spawn. This study advances our understanding about the functioning of an established MPA and provides important insights into the biology and management of a small sedentary species, suggesting the relevance of rare but important fish behaviours.
Author: Aspillaga, Bartumeus, Linares, Starr, López-Sanz, Díaz, Zabala, Hereu

Title: Seasonal and ontogenetic movements of lingcod (Ophiodon elongatus) in central california, with implications for marine protected area management
Description: Movements of lingcod implanted with acoustic transmitters were monitored for a year in central California. Half of the tagged lingcod remained within 5 km of coastline for at least 50% of days in the year, and 30% of lingcod were detected for >80% of the study days. Lingcod demonstrated distinct patterns in residency that were correlated to sex, fish length, and season. Residence times of females decreased with total length; female lingcod >90% maturity were present during the fall spawning season and briefly during the spring. Size-specific movements were less pronounced for males, but daily detections of males declined in spring, at the end of the winter nest-guarding season. The majority of lingcod detections were constrained to a limited area, however a few lingcod exhibited movements up to several kilometers. These results indicate that marine reserves can serve to both protect lingcod and also provide fisheries benefits via spillover. © 2016,Scripps Institution of Oceanography. All rights reserved., Article
Author: Greenley, Green, Starr

Title: Utilizing fishermen knowledge and expertise: Keys to success for collaborative fisheries research
Description: Collaborative fisheries research provides a mechanism for integrating the unique knowledge, experience, and skills of fishermen and scientists. It is a joint intellectual endeavor that begins with the inception of a project and continues until its final stages, with each group having mutual investment in-and ownership of- the project. Collaborative fisheries research promotes communication and trust among fishermen, scientists, and managers and can provide much-needed scientifically valid data for fisheries management. It can enhance federal and state management data collection programs, which span broad sections of coastline, by increasing the ability to detect changes in local metapopulations that may be overfished or underutilized. We describe a methodology for conducting collaborative fisheries surveys and apply it to marine protected areas along the central California coast. During a series of workshops in 2006, attended by members of the fishing, academic, environmental, and management communities, protocols were established for conducting hook-and-line surveys collaboratively with commercial passenger fishing vessel captains and volunteer recreational anglers. The protocols have been implemented annually since 2007. This case study highlights the effectiveness of-and the essential steps in-developing our collaborative fisheries research and monitoring projects., Cited By (since 1996):1, Fish and Fisheries
Author: Yochum, Starr, Wendt
Date: 2011-01-01T00:00:00Z