Recent Submissions

  • Preliminary Stock Structure of Coastal Bottlenose Dolphins along the Atlantic Coast of the US

    Southeast Fisheries Science Center, National Marine Fisheries Service (U.S.) (2001-06)
    Recent analyses have identified multiple stocks of bottlenose dolphins along the Atlantic coast from New Jersey to central Florida. Although drawing stock boundaries is confounded by the migratory pattern of the northernmost stock and by the unequal distribution of samples both spatially and temporally, results to date indicate the likelihood of a high level of structuring. In order to estimate abundance, the offshore range of the coastal morphotype of bottlenose dolphin also has been tentatively identified. That range is different north and south of Cape Hatteras; north of Cape Hatteras, evidence suggests that the coastal morphotype generally inhabits a range from the coast to 12km from shore, while south of Cape Hatteras, the range extends to 27km. Using both sets of results (latitudinal and longitudinal), management units can be defined for the purpose of evaluating the potential effects of fisheries mortality: 1. Northern Migratory Unit: In summer, this stock is found primarily from the NC/VA state line to the northern limit of the range (NJ or NY). In winter, this stock migrates out of the northern coastal areas and at least some of the animals are found off the coast of NC, where they spatially overlap with the northern and southern NC units. 2. Northern NC Unit: In summer, this unit consists of dolphins along the coast of NC from Cape Lookout to the VA/NC line and dolphins that reside in northern estuaries in this region. There is some evidence of dolphins moving between estuaries and the coast. There may also be spatial overlap between this unit and the southern NC unit in summer, at least in the estuaries near Cape Lookout. In winter, this unit occurs along the coast or estuaries of NC, where it spatially overlaps with the migratory unit and the southern NC unit. 3. Southern NC Unit: In summer, dolphins in this unit are found primarily along the coast of NC from south of Cape Lookout, NC, to Murrell's Inlet, SC. There may also be spatial overlap between this unit and the northern NC unit in summer, at least in the estuaries near Cape Lookout. In winter, these dolphins are assumed to be in the same areas, where they may spatially overlap with the migratory unit and with the Northern NC unit. 4. South Carolina Management Units: This management unit encompasses dolphins south of Murrell’s Inlet, SC, (the southern NC Unit) and the SC/GA state line. Seasonal movements that might result in spatial overlap between this stock and any others have not been defined. 5. Georgia Management Unit: This management unit encompasses dolphins in coastal and estuarine waters of Georgia. Seasonal movements that might result in spatial overlap between this stock and any others have not been defined. 6. Northern Florida Management Unit: This management unit includes dolphins from the FL/GA state line to the north end of the Indian/Banana River Lagoon system. 7. Central Florida Management Unit: This management unit begins south of the northern management unit and has an undefined southern boundary because of lack of information south of the Indian/Banana River system. However, consistent with results from areas to the north, it is precautionary to assume that this stock does not range as far south as southern Florida.
  • Taxonomic review and meristic variation in marine sculpins (Osteichthyes:Cottidae) of the northeast Pacific Ocean

    Howe, Kevin M.; Richardson, Sally L. (U.S. NOAA National Marine Service, Northwest and Alaska Fisheries Center, 1978-09-30)
    Within the northeast Pacific Ocean (Baja California to the Aleutian Islands), 40 genera comprising 90 species of sculpins (Cottidae) have been recorded; this includes two members of the freshwater genus Cottus which are often found in nearshore marine waters. The species are listed and their distributions are indicated. At present, only one family, Cottidae, should be recognized for the sculpins. Each genus is discussed in terms of taxonomic problems and affinities and each is also diagnosed, indicating differentiating characteristics. Some genera should be synonymized and these are indicated although no formal synonymies are proposed at this time. In addition, other genera need to be studied as they appear closely related to other genera and might be synonymized without any loss of information. The species in some genera (i.e. Artediellus, Hemitripterus, Icelinus, Icelus, Malacocottus, Myoxocephalus, Triglops) are in serious need of study. Some of the species within these genera, as well as many species in other genera are noticably rare in museum collections. Each species within the northeast Pacific is also diagnosed and comments on depth distribution and relative rarity are provided. Meristic data compiled from museum specimens is provided for each genus as well as each species. Artificial keys to the cottid genera and cottid species in the northeast Pacific Ocean are included.
  • A science-based seagrass survey window for coastal construction project planning in Florida

    Karazsia, Jocelyn (NOAA National Marine Fisheries Service, Southeast Region, 2010-05-01)
    A variety of construction activities occur in or near estuarine and coastal waters of Florida within habitats that may support seagrass. Resource managers have a need for a science-based seagrass survey window for Florida to ensure that habitats are adequately mapped and characterized prior to authorizing the destruction or modification of the habitat. The development of a survey window requires a balance between physical factors that maximize the ability to detect seagrass during sampling (essentially water clarity) and the time of year that supports peak biomass and distribution. Of the seven seagrass species found in Florida, two species exhibit greater seasonality: Halophila decipiens and Halodule wrightii. Several publications were synthesized that refer to the seasonality of seagrass. Based on this review and consultation with leading seagrass scientists, surveys for these seagrass species should occur June 1 through September 30. Results from surveys conducted outside this window will require careful evaluation given the likelihood that seagrass distribution or extent is underrepresented. This recommendation differs from but is not in conflict with recommendations from NMFS Protected Resources Division for Johnson's seagrass, Halophila johnsonni, which exhibits a life history that makes year-round sampling less problematic than it is for Halophila decipiens and Halodule wrightii. Because Halophila decipiens and Halodule wrightii are within the range of Halophila johnsonii, conducting surveys within the June 1 to September 30 window could eliminate the need for multiple surveys.
  • Growth and age study of Pacific hagfish (Eptatretus stoutii) off the central California coast

    Nakamura, Royden (California Polytechnic State University, 1994-03-07)
    The recent development of a short term, but very intense fishery for Pacific hagfish (Eptatretus stoutii) on the Pacific Coast of North America prompted concern over the absence of management and conservation guidelines for this species. However, very little is known of the biology of hagfish, particularly with regard to information applicable to fishery resource management. Growth and population age-size structure data are among critical categories of information that are non-existent to date. This project obtained primary growth information from field and laboratory studies as well as comprehensive population size composition data.
  • Estimates of cetacean abundance in the northern Gulf of Mexico from vessel surveys

    Hansen, Larry J.; Mullin, Keith D.; Roden, Carol L. (National Marine Fisheries Service, Southeast Fisheries Science Center, 1995)
    The Southeast Fisheries Science Center (SEFSC) initiated annual, vessel-based visual sampling surveys of northern Gulf of Mexico marine mammals in 1990. The primary goal of these surveys was to meet Marine Mammal Protection Act requirements for estimating abundance and monitoring trends of marine mammal stocks in United States waters. The surveys were designed to collect: 1) marine mammal sighting data to estimate abundance and to determine distribution and diversity; and 2) environmental data to evaluate factors which may affect the distribution, abundance and diversity of marine mammals. The analyses for abundance estimation from the 1991-1994 surveys are presented in this report.
  • Preliminary estimates of cetacean abundance in the northern Gulf of Mexico, and of selected cetacean species in the U.S. Atlantic Exclusive Economic Zone from vessel surveys

    Hansen, Larry J.; Mullin, Keith D.; Roden, Carol L. (National Marine Fisheries Service, Southeast Fisheries Science Center, 1995)
    The Southeast Fisheries Science Center (SEFSC) initiated annual, vessel-based visual sampling surveys of northern Gulf of Mexico marine mammals in 1990 and conducted a similar survey in U.S. Atlantic Exclusive Economic Zone (EEZ) waters from Miami, Florida, to Cape Hatteras, North Carolina, in 1992. The primary goal of these surveys was to meet Marine Mammal Protection Act requirements for estimating abundance and monitoring trends of marine mammal stocks in United States waters. The surveys were designed to collect: 1) marine mammal sighting data to estimate abundance and to determine distribution and diversity; and 2) environmental data to evaluate factors which may affect the distribution, abundance and diversity of marine mammals. The preliminary analyses for abundance estimation from the 1990-1993 surveys are presented in this report.
  • Report on the biology of Pacific hagfish, Eptatretus stouti and the development of its fishery in California

    Kato, Susumu (NOAA National Marine Fisheries Service, Southwest Region, 1990-08-03)
    Hagfish, often referred to as "slime eels", are familiar to most fishermen as pests that frequently devour fish caught by trap, hook, and gillnet. In the Republic of Korea (ROK or South Korea), however, hagfish are sought after as valuable fish not only for their edible flesh, but also for their skin, which is processed into leather used to make expensive purses, shoes, and other articles. In fact, because of a shortage of hagfish in the waters near the ROK, the leather industry there has started to import hagfish, first from Japan in the mid 1980's, then from the United States starting in 1988.This report describes the nascent fishery for Eptatretus stouti (Pacific hagfish) in California, and includes aspects of its life history. The hagfish industry in the ROK is also briefly described.
  • Preliminary study on the use of neural arches in the age determination of bluntnose sixgill sharks (Hexanchus griseus)

    McFarlane, Gordon A.; King, Jacquelynne R.; Saunders, Mark W. (2002)
    Fishery Bulletin
  • Properties of the residuals from two tag-recovery models

    Latour, Robert J.; Hoenig, John M.; Pollock, Kenneth H. (2002)
    Fishery Bulletin
  • Re-identification of a lamnid shark embryo

    Mollet, Henry F.; Testi, Antonio D.; Compagno, Leonard J. V.; Francis, Malcolm P. (2002)
    Fishery Bulletin
  • Distribution and co-occurrence of rockfishes (family: Sebastidae) over trawlable shelf and slope habitats of California and southern Oregon

    Williams, Erik H.; Ralston, Stephen (2002)
    Fishery Bulletin
    The rockfishes of the sebastid genus Sebastes are a very important fishery resource off the coasts of California and southern Oregon. How-ever, many of the 54 managed stocks of west coast rockfish have recently reached historically low population levels, leading fishery managers to re-examine current management practices. Management of rockfish stocks as multispecies aggregates, as opposed to independent stocks within the ground-fish fishery, can be more desirable when nontargeted bycatch, discard, and management complexity are considered. Rockfish assemblage structure and species co-occurrences were determined by using data from the Alaska Fisheries Science Center triennial continental shelf bottom trawl survey. The weight of rockfish species in trawl catches was expressed as a catch-per-unit-of-effort (CPUE) statistic, from which species spatial distributions, overlaps, diversity, and richness were analyzed. Multidimensional scaling of transformed CPUE data was employed in indirect gradient and multivariate partitioning analyses to quantify assemblage relationships. Results indicated that rockfish distributions closely match the bathymetry of coastal waters. Indirect gradient analysis suggested that depth and latitude are the principal factors in structuring the spatial distributions of rockfish on trawlable habitat. In addition, four assemblages were identified through the joint evaluation of species’ distributions and multivariate partitioning analyses: 1) deep-water slope; 2) northern shelf; 3) southern shelf; and 4) nearshore. The slope, shelf, and near-shore groups are found in depth ranges of 200–500 m, 100–250 m, and 50–150 m, respectively. The division of northern and southern shelf assemblages occurs over a broad area between Cape Mendocino and Monterey Canyon. The results of this analysis are likely to have direct application in the management of rockfish stocks off the coasts of southern Oregon and California.
  • Sustainability of elasmobranchs caught as bycatch in a tropical prawn (shrimp) trawl fishery

    Stobutzki, Ilona C.; Miller, Margaret J.; Heales, Don S.; Brewer, David T. (2002)
    Fishery Bulletin
    The bycatch of Australia’s northern prawn fishery (NPF) comprises 56 elasmobranch species (16 families). The impact of this fishery on the sustainability of these species has not been addressed. We obtained estimates of catch rates and the within-net survival of elasmobranchs. Carcharhinus tilstoni, C. dussumieri, Rhynchobatus djiddensis, and Himantura toshi represented 65% of the bycatch. For most species, >50% of individuals in the bycatch were immature, and some species recruited to the fishery at birth. For all species combined, 66% of individuals in the bycatch died in the trawl net.The relative sustainability of elasmobranchs caught as bycatch was examined by ranking species with respect to their susceptibility to capture and mortality due to prawn trawling and with respect to their capacity to recover once the population was depleted. The species that were least likely to be sustainable were four species of pristids, Dasyatis brevicaudata, and Himantura jenkinsii. These are bottom-associated batoids that feed on benthic organisms and are highly susceptible to capture in prawn trawls. The recovery capacity of these species was also low according to our criteria. Our results provide a valuable first step towards ensuring the sustainability of elasmobranchs that are caught as bycatch by highlighting species for management and research. The effectiveness of turtle excluder devices (TEDs) in reducing elasmobranch bycatch varied greatly among species but was generally not very effective because most of the captured species were small.
  • Age and growth of the swordfish (Xiphias gladius L.) in the waters around Taiwan determined from anal-fin rays

    Sun, Chi-Lu; Wang, Sheng-Ping; Yeh, Su-Zan (2002)
    Fishery Bulletin
    Age and growth of the swordfish (Xiphias gladius) in Taiwan waters was studied from counts of growth bands on cross sections of the second ray of the first anal fin. Data on lower jaw fork length and weight, and samples of the anal fin of male and female swordfish were collected from three offshore and coastal tuna longline fishing ports on a monthly basis between September 1997 and March 1999. In total, 685 anal fins were collected and 627 of them (293 males and 334 females) were aged successfully. The lower jaw fork lengths of the aged individuals ranged from 83.4 to 246.6 cm for the females and from 83.3 to 206 cm for the males.The radii of the fin rays and growth bands on the cross sections were measured under a dissecting microscope equipped with an image analysis system. Trends in the monthly marginal increment ratio indicated that growth bands formed once a year. Thus, the age of each fish was deter-mined from the number of visible growth bands. Two methods were used to estimate and compare the standard and the generalized von Bertalanffy growth parameters for both males and females. The nonlinear least square estimates of the generalized von Bertalanffy growth parameters in method II, in which a power function was used to describe the relationship between ray radius and LJFL, were recommended as most acceptable. There were significant differences in growth parameters between males and females. The growth parameters estimated for females were the following: asymptotic length (L∞) = 300.66 cm, growth coefficient (K) = 0.040/yr, age at zero length (t0) = –0.75 yr, and the fitted fourth parameter (m) = –0.785. The growth parameters estimated for males were the following: asymptotic length (L∞) = 213.05 cm, growth coefficient (K) = 0.086/yr, age at zero length (t0) = –0.626 yr, and the fitted fourth parameter (m) = –0.768.
  • An evaluation of back-calculation methodology using simulated otolith data

    Schirripa, Michael J. (2002)
    Fishery Bulletin
    I simulated somatic growth and accompanying otolith growth using an individual-based bioenergetics model in order to examine the performance of several back-calculation methods. Four shapes of otolith radius-total length relations (OR-TL) were simulated. Ten different back-calculation equations, two different regression models of radius length, and two schemes of annulus selection were examined for a total of 20 different methods to estimate size at age from simulated data sets of length and annulus measurements. The accuracy of each of the twenty methodswas evaluated by comparing the back-calculated length-at-age and the true length-at-age. The best back-calculation technique was directly related to how well the OR-TL model fitted. When the OR-TL was sigmoid shaped and all annuli were used, employing a least squares linear regression coupled with a log-transformed Lee back-calculationequation (y-intercept corrected) resulted in the least error; when only the last annulus was used, employing adirect proportionality back-calculation equation resulted in the least error. When the OR-TL was linear, employinga functional regression coupled with the Lee back-calculation equation resulted in the least error when all annuli were used, and also when only the last annulus was used. If the OR-TL was exponentially shaped, direct substitution into the fitted quadratic equation resulted in the least error when all annuli were used, and when only thelast annulus was used. Finally, an asymptotically shaped OR-TL was best modeled by the individually corrected Weibull cumulative distribution function when all annuli were used, and when only the last annulus was used.
  • Movements, behavior, and habitat selection of bigeye tuna (Thunnus obesus) in the eastern equatorial Pacific, ascertained through archival tags

    Schaefer, Kurt M.; Fuller, Daniel W. (2002)
    Fishery Bulletin
    Ninety-six bigeye tuna (88– 134 cm fork length) were caught and released with implanted archival (electronic data storage) tags near fish-aggregating devices (FADs) in the equatorial eastern Pacific Ocean (EPO) during April 2000. Twenty-nine fish were recaptured, and the data from twenty-seven tags were successfully downloaded and processed. Time at liberty ranged from 8 to 446 days, and data for 23 fish at liberty for 30 days or more are presented. The accuracy in geolocation estimates, derived from the light level data, is about 2 degrees in latitude and 0.5 degrees in longitude in this region. The movement paths derived from the filtered geolocation estimates indicated that none of the fish traveled west of 110°W during the period between release and recapture. The null hypothesis that the movement path is random was rejected in 17 of the 22 statistical tests of the observed movement paths. The estimated mean velocity was 117 km/d. The fish exhibited occasional deep-diving behavior, and some dives exceeded 1000 m where temperatures were less than 3°C. Evaluations of timed depth records, resulted in the discrimination of three distinct behaviors: 54.3% of all days were classified as unassociated (with a floating object) type-1 behavior, 27.7% as unassociated type-2 behavior, and 18.7% as behavior associated with a floating object. The mean residence time at floating objects was 3.1 d. Data sets separated into day and night were used to evaluate diel differences in behavior and habitat selection. When the fish were exhibiting unassociated type-1 behavior (diel vertical migrations), they were mostly at depths of less than 50 m (within the mixed layer) throughout the night, and during the day between 200 and 300 m and 13° and 14°C. They shifted their average depths in conjunction with dawn and dusk events, presumably tracking the deep-scattering layer as a foraging strategy. There were also observed changes in the average nighttime depth distributions of the fish in relation to moon phase.
  • An examination of spatial and temporal genetic variation in walleye pollock (Theragra chalcogramma) using allozyme, mitochondrial DNA, and microsatellite data

    Olsen, Jeffrey B.; Merkouris, Susan E.; Seeb, James E. (2002)
    Fishery Bulletin
    We used allozyme, microsatellite, and mitochondrial DNA (mtDNA) data to test for spatial and interannual genetic diversity in wall-eye pollock (Theragra chalcogramma) from six spawning aggregations representing three geographic regions: Gulf of Alaska, eastern Bering Sea, and eastern Kamchatka. Interpopulation genetic diversity was evident primarily from the mtDNA and two allozyme loci (SOD-2*, MPI*). Permutation tests ˆindicated that FST values for most allozyme and microsatellite loci were not significantly greater than zero. The microsatellite results suggested that high locus polymorphism may not be a reliable indicator of power for detecting population differentiation in walleye pollock. The fact that mtDNA revealed population structure and most nuclear loci did not suggests that the effective size of most walleye pollock populations is large (genetic drift is weak) and migration is a relatively strong homogenizing force. The allozymes and mtDNA provided mostly concordant estimates of patterns of spatial genetic variation. These data showed significant genetic variation between North American and Asian populations. In addition, two spawning aggregations in the Gulf of Alaska, in Prince William Sound, and off Middleton Island, appeared genetically distinct from walleye pollock spawning in the Shelikof Strait and may merit management as a distinct stock. Finally, we found evidence of interannual genetic variation in two of three North American spawning aggregations, similar in magnitude to the spatial variation among North American walleye pol-lock. We suggest that interannual genetic variation in walleye pollock may be indicative of one or more of the following factors: highly variable reproductive success, adult philopatry, source-sink metapopulation structure, and intraannual variation (days) in spawning timing among genetically distinct but spatially identical spawning aggregates.
  • Integration of submersible transect data and high-resolution multibeam sonar imagery for a habitat-based groundfish assessment of Heceta Bank, Oregon

    Nasby-Lucas, Nicole M.; Embley, Bob W.; Hixon, Mark A.; Merle, Susan G.; Tissot, Brian N.; Wright, Dawn J. (2002)
    Fishery Bulletin
    In the face of dramatic declines in groundfish populations and a lack of sufficient stock assessment information, a need has arisen for new methods of assessing groundfish populations. We describe the integration of seafloor transect data gathered by a manned submersible with high-resolution sonar imagery to produce a habitat-based stock assessment system for groundfish. The data sets used inthis study were collected from Heceta Bank, Oregon, and were derived from 42 submersible dives (1988–90) and a multibeam sonar survey (1998). The submersible habitat survey investigated seafloor topography and groundfish abundance along 30-minute transects over six predetermined stations and found a statistical relationship between habitat variability and groundfish distribution and abundance. These transects were analyzed in a geographic information system (GIS) by using dynamic segmentation to display changes in habitat along the transects. We used the submersible data to extrapolate fish abundance within uniform habitat patches over broad areas of the bank by means of a habitat classification based on the sonar imagery. After applying a navigation correction to the submersible-based habitat segments, a good correlation with major boundaries on the backscatter and topographic boundaries on the imagery were apparent. Extrapolation of the extent of uniform habitats was made in the vicinity of the dive stations and a preliminary stock assessment of several species of demersal fish was calculated. Such a habitat-based approach will allow researchers to characterize marine communities over large areas of the seafloor.
  • The reproductive biology of the porbeage shark (Lamna nasus) in the western North Atlantic Ocean

    Jensen, Christopher F.; Natanson, Lisa J.; Pratt Jr., Harold L.; Kohler, Nancy; Campana, Steven E. (2002)
    Fishery Bulletin
    Reproductive organs from 393 male and 382 female porbeagles (Lamna nasus), caught in the western North Atlantic Ocean, were examined to determine size at maturity and reproductive cycle. Males ranged in size from 86 to 246 cm fork length (FL) and females ranged from 94 to 288 cm FL. Maturity in males was best described by an inflection in the relationship of clasper length to fork length when combined with clasper calcification. Males matured between 162 and 185 cm FL and 50% were mature at 174 cm FL. In females, all reproductive organ measurements related to body length showed a strong inflection around the size of maturity. Females matured between 210 and 230 cm FL and 50% were mature at 218 cm FL. After a protracted fall mating period (September–November), females give birth to an average of 4.0 young in spring (April−June). As in other lamnids, young are nourished through oophagy. Evidence from this study indicated a one-year reproductive cycle and gestation period lasting 8–9 months.
  • The measurement error in marine survey catches: the bottom trawl case

    Hjellvik, Vidar; Godo, Olav Rune; Tjostheim, Dag (2002)
    Fishery Bulletin
    We have formulated a model for analyzing the measurement error in marine survey abundance estimates by using data from parallel surveys (trawl haul or acoustic measurement). The measurement error is defined as the component of the variability that cannot be explained by covariates such as temperature, depth, bottom type, etc. The method presented is general, but we concentrate on bottom trawl catches of cod (Gadus morhua). Catches of cod from 10 parallel trawling experiments in the Barents Sea with a total of 130 paired hauls were used to estimate the measurement error in trawl hauls. Based on the experimental data, the measurement error is fairly constant in size on the logarithmic scale and is independent of location, time, and fish density. Compared with the total variability of the winter and autumn surveys in the Barents Sea, the measurement error is small (approximately 2–5%, on the log scale, in terms of variance of catch per towed distance). Thus, the cod catch rate is a fairly precise measure of fish density at a given site at a given time.

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