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Title: Trophic ecology of the gopher rockfish Sebastes carnatus inside and outside of central California marine protected areas
Description: Marine protected areas (MPAs) can potentially alter food web dynamics by increasing the density of fishes within their borders. Such increases in the density of potential competitors can cause generalist predators to contract the scope of their diets. This study investigated the effects of increased conspecific fish density on the diets of gopher rockfish Sebastes carnatus at a 35 yr old MPA in Point Lobos, California, and at 4 newly established MPAs in Año Nuevo, Point Lobos, Piedras Blancas, and Point Buchon in central California. Analyses were conducted for 707 stomachs collected from 2007 to 2009. Diets did not differ inside versus outside the old Point Lobos MPA in terms of prey richness, evenness, composition, or gopher rockfish trophic level. However, fish outside the MPA had greater levels of individual specialization. No consistent differences in these metrics were observed inside versus outside the 4 new MPAs, although prey composition and evenness did differ significantly among geographic locations. Diets at Año Nuevo, the most northern and shallow location, consisted predominantly of Cancer spp. and porcelain crabs (Porcellanidae), while diets from southern, deeper locations were dominated by brittle stars (Ophiuroidea). The case study of the old Point Lobos MPA indicates that fish feeding ecology may not change in an MPA after several decades. Differences in prey observed among geographic locations suggest variation in the community composition among central California's new MPAs, which may influence the effect of each MPA on food web dynamics over time. Copyright © 2015 Inter-Research., Export Date: 19 October 2015
Author: Loury, Bros, Starr, Ebert, Cailliet
Date: 2015-01-01T00:00:00Z

Title: Food habits of the sandpaper skate, Bathyraja kincaidii (Garman, 1908) off central California,
Description: The stomachs of 130 sandpaper skates, Bathyraja kincaidii (Garman, 1908), were sampled from off central California to determine their diet composition. The overall diet was dominated by euphausiids, but shrimps, polychaetes and squids were also important secondary prey. A three-factor MANOVA demonstrated significant differences in the diet by sex, maturity status and oceanographic season using numeric and gravimetric measures of importance for the major prey categories. These three main factors explained more variation in diet than interactions between the factors, and season explained the most variance overall. A detailed analysis of the seasonal variation among the prey categories indicated that abundance changes in the most important prey, euphausiids, were coupled with seasonal changes in the importance of other prey. When upwelling occurred and productivity was great (Upwelling and Oceanic seasons), euphausiids were likely highly abundant in the study area and were the most important prey for B. kincaidii. As productivity declined (Davidson Current season), euphausiids appeared to decrease in abundance and B. kincaidii switched to secondary prey. At that time, gammarid amphipods and shrimps became the most important prey items and polychaetes, mysids and euphausiids were secondary. © 2007 Springer Science+Business Media, Inc., Cited By (since 1996):15, CODEN: EBFID, ,
Author: Rinewalt, Ebert, Cailliet
Date: 2007-01-01T00:00:00Z

Title: Age, growth, and maturity of the whitebrow skate, Bathyraja minispinosa, from the eastern Bering Sea,
Description: Skates are a common bycatch in groundfish fisheries in the Bering Sea; however, their life-history characteristics are not well known. The study is the first to investigate the age, growth, and age at maturity of Bathyraja minispinosa. Ages were estimated using sectioned vertebrae and several growth models were compared. The Gompertz model was the best fit and no significant differences were detected between sexes for any model. The maximum age estimated was 37 years, and parameter estimates generated from the three-parameter von Bertalanffy model were k 0.02 year -1 and L∞ 146.9 cm total length (TL). Males reached their size at 50 maturity larger than females (70.1 and 67.4 cm, respectively), but no significant differences in the estimated size or age at maturity were found. Whereas B. minispinosa is smaller than many skate species in the eastern Bering Sea, it has a considerably longer estimated lifespan, indicating that size may not be a reliable method of estimating the vulnerability of a rajid species to population declines in the eastern North Pacific. © 2011 International Council for the Exploration of the Sea., Cited By (since 1996):1, Fish and Fisheries, CODEN: ICESE, ,
Author: Ainsley, Ebert, Cailliet
Date: 2011-01-01T00:00:00Z

Title: Comparative age and growth of the Aleutian skate, Bathyraja aleutica, from the eastern Bering Sea and Gulf of Alaska
Description: The Aleutian skate (Bathyraja aleutica) is a large deep-water species that commonly occurs in bycatch of Alaskan trawl and longline fisheries. Although prominent in the skate biomass of the eastern Bering Sea (EBS) and Gulf of Alaska (GOA) ecosystems, minimal biological information exists. To increase our understanding of this potentially vulnerable species, and address the possibility of two separate populations in Alaskan waters, the age and growth of B. aleutica was studied. Vertebral centra were examined for age determination, and multiple growth models were evaluated to determine growth characteristics. Skates from the EBS attained maximum ages of 17 and 16 years for females and males, respectively, and the two-parameter von Bertalanffy growth functions generated estimates of k = 0.13 yr.-1 and L∞ = 162.1 cm for females, with similar results for males. Skates from the GOA reached 19 years in females and 18 years in males. Growth parameters of female skates from the GOA were estimated as k = 0.11 yr.-1 and L∞ = 160.0 cm, whereas males grew faster, with estimates of k = 0.15 yr.-1 and L∞ = 138.2 cm. The results of this study may indicate the presence of distinct populations of B. aleutica in the eastern North Pacific.
Author: Haas, Ebert, Cailliet

Title: Reproductive biology of two commercially exploited skates, Raja binoculata and R. rhina, in the western Gulf of Alaska,
Description: This study provides the first detailed information on the reproductive biology of two large and abundant eastern North Pacific Ocean skate species: big skate (Raja binoculata) and longnose skate (Raja rhina). Skates were collected in the western Gulf of Alaska during 2005 and 2006 after a targeted fishery for these two species developed around Kodiak Island, Alaska; both species are also taken as by-catch to other fisheries. A total of 307 females (20.1-183.3 cm TL) and 138 males (19.5-143.7 cm TL) R. binoculata, and 354 females (18.1-145.0 cm TL) and 318 males (21.1-135.8 cm TL) R. rhina were collected. Female R. binoculata were found to attain first (e.g., smallest individual) maturity at 125.8 cm TL and 50% at 148.6 cm TL. Males were found to attain first and 50% maturity at 124.0 and 119.2 cm TL, respectively. No gravid female R. binoculata, with egg cases in utero, were encountered during the study. Female R. rhina were found to attain first and 50% maturity at 102.2 and 113.1 cm TL, respectively. Gravid female R. rhina, with egg cases in utero, were recorded throughout the sampling period. Males attained first maturity at 101.0 cm TL and 50% maturity at 102.9 cm TL. Histological analysis did not reveal significant changes in spermatocyst production for either species during the sampling period. Both species appear to be reproductively active year-round as no seasonal cycle was evident. This study provides new and essential information on the reproductive biology of these two commercially targeted skate species. © 2008 Elsevier B.V. All rights reserved., Cited By (since 1996):8, CODEN: FISRD, ,
Author: Ebert, Smith, Cailliet
Date: 2008-01-01T00:00:00Z

Title: Reproductive biology of deep-sea catsharks (Chondrichthyes: Scyliorhinidae) in the eastern North Pacific,
Description: Apristurus brunneus, A. kampae, and Parmaturus xaniurus were caught by trawl and longline between Washington and southern California (48°N to 32°N latitude) from June 2001 through October 2004. In females, oviducal gland width increased with TL in all three species but remained within 4 to 6% of TL. Oocyte diameter increased with TL during reproductive development in all species, and continued to increase with size after reproductive maturity was reached. The weight-length relationships differed significantly among species but not between sexes of any species from the eastern North Pacific combined. Using logistic regression, it was determined that total length at 50% maturity (TL50) of A. brunneus males was 514 mm TL and all A. brunneus males were mature at 547 mm TL. Female A. brunneus reached TL50 at 501 mm TL and all female A. brunneus were mature at 581 mm TL. Apristurus kampae males and females reached TL50 at approximately 485 mm TL and 490 mm TL, respectively. Parmaturus xaniurus males reached TL50 at 444 mm TL and females at 501 mm TL. Gravid female A. brunneus were found in all months of the year, but gravid P. xaniurus were found primarily June through September. Adult A. kampae females were found only in July through November and there were gravid females in all these months. Based upon gonadosomatic indices, I G, these species may mate within a defined period of time (April through June); however, A. brunneus appear to reproduce throughout the year and P. xaniurus reproduce within a defined season (approximately July through September). © 2006 Springer Science+Business Media, Inc., Cited By (since 1996):7, CODEN: EBFID, ,
Author: Flammang, Ebert, Cailliet
Date: 2008-01-01T00:00:00Z

Title: Comparative Demography of Skates: Life-History Correlates of Productivity and Implications for Management
Description: Age-structured demographic models were constructed based on empirical estimates of longevity and maturity for five deepwater Bering Sea skates to investigate how observed differences in life history parameters affect population growth rates. Monte Carlo simulations were used to incorporate parameter uncertainty. Estimated population growth rates ranged from 1.045 to 1.129 yr-1 and were lower than those reported for other Alaskan skates and most chondrichthyans. Population growth rates of these and other high-latitude skates increased with relative reproductive lifespan, but displayed no significant relationship with body size or depth distribution, suggesting that assemblage shifts may be difficult to predict for data-poor taxa. Elasticity analyses indicated that juvenile and adult survival had greater per-unit effects on population growth rates than did egg-case survival or fecundity. Population growth rate was affected more by uncertainty in age at maturity than maximum age. The results of this study indicate that if skates are deemed to be a management concern, gear modifications or depth-specific effort controls may be effective. © 2013 Barnett et al., Fish and Fisheries, Art. No.: e65000
Author: Barnett, Winton, Ainsley, Cailliet, Ebert
Date: 2013-01-01T00:00:00Z

Title: Pristiophorus nancyae, a new species of sawshark (Chondrichthyes: Pristiophoridae) from Southern Africa,
Description: A new species of sawshark, Pristiophorus nancyae sp. nov., is described from eight specimens collected off Mozambique. The new species is the second member of the family Pristiophoridae and first member of the genus Pristiophorus described from the western Indian Ocean. The new Pristiophorus species can be distinguished from the sympatric occurring six-gilled sawshark, Pliotrema warreni Regan, 1906, most notably by having five paired gill openings as opposed to six. The new species is distinguished from all other Pristiophorus species by several distinctive characteristics. Most notably, the new species differs by having a very distinctive double row of four to five conspicuous large pits anterior to the nasal barbels on the underside of its snout. Other distinguishing characteristics include a broad, triangular first dorsal fin with a rear tip that extends behind the pelvic midbases, barbels much closer to mouth than snout tip, two rows of enlarged pits on the underside of the pre-barbel rostrum, ridges on the base of its large lateral rostral teeth, mostly tricuspidate, flat, imbricated lateral trunk denticles, and plain color pattern. The new species is compared to the five other known Pristiophorus species and a revised key to the genus is presented. © 2011 Rosenstiel School of Marine and Atmospheric Science of the University of Miami., , ,
Author: Ebert, Cailliet
Date: 2011-01-01T00:00:00Z

Title: Age and growth of the sandpaper skate, Bathyraja kincaidii, using vertebral centra, with an investigation of caudal thorns,
Description: The sandpaper skate, Bathyraja kincaidii, is one of four skate species commonly taken in trawl fisheries off central California although very little is known about its life history. In this study, age and growth were evaluated from 187 vertebrae using a common growth band counting method. An attempt to use marginal increment analysis and centrum edge analysis failed to validate the annual periodicity of growth band formation; however, it is a valid assumption based on structural similarity from other studies. Assuming annual band formation, von Bertalanffy growth parameters were determined for females (L ∞ = 537.3 mm; k = 0.237; t o = -1.629; N = 99) and males (L ∞ = 580.2 mm; k = 0.185; to = -2.530; N = 88). Maximum likelihood ratios indicated no significant difference (P > 0.05) between male and female von Bertalanffy growth parameters, thus data were combined (L ∞ = 557.8 mm; k = 0.207; t o = -2.147; N = 187). Age estimates from band counts in vertebral centra indicated a minimum longevity of 17 and 18 years for female and male B. kincaidii, respectively. Caudal thorns were also assessed for age analyses, but were deemed unreliable and could not be used to verify age estimates from vertebral centra. © Copyright Marine Biological Association of the United Kingdom 2010., Cited By (since 1996):1, Fish and Fisheries, CODEN: JMBAA, ,
Author: Perez, Cailliet, Ebert
Date: 2011-01-01T00:00:00Z

Title: A comparison of reproductive parameters of the Bering skate, Bathyraja interrupta, from two Alaskan large marine ecosystems,
Description: Estimates of size at maturity are crucial to fisheries stock assessments and may change spatially and temporally. This study directly compares life-history characteristics of a skate species in two large marine ecosystems in a region where there is both a directed fishery and considerable skate by-catch in other fisheries. The Bering skate, Bathyraja interrupta, is one of the most common skate species in Alaskan waters, occurring in two large marine ecosystems, the eastern Bering Sea (EBS) and the Gulf of Alaska (GOA), but little is known about its life history. Skates were sampled from both regions between 2004 and 2007. In the GOA, the size at maturity was estimated to be 69cm total length(TL) for males and 71cmTL for females, while in the EBS size at maturity was estimated as 70cm and 72cmTL for males and females, respectively. Median size at maturity differed by sex but not by region. Our results indicate that B. interrupta shows late maturity, typical of most skate species, suggesting that more detailed monitoring of skate populations and precautionary management is warranted as skate fisheries expand. © CSIRO 2011., Cited By (since 1996):2, Fish and Fisheries, CODEN: AJMFA, ,
Author: Ainsley, Ebert, Cailliet
Date: 2011-01-01T00:00:00Z

Title: Egg cases of the genus Apristurus (Chondrichthyes: Scyliorhinidae),
Description: The genus Apristurus has been divided formerly into three species subgroups based on morphological and molecular phylogenies. Previous studies have agreed on the separation into distinct species groups, the largest two of which have been described as the brunneus and spongiceps groups. An examination of the egg cases produced by these oviparous catsharks corroborates the distinction in species groups: egg cases of the brunneus group have long fibrous and curly tendrils at either end, whereas egg cases of the spongiceps group lack tendrils. The egg cases of A. kampae, A. manis, A. spongiceps and Apristurus sp. D are described for the first time, and the egg cases of A. brunneus and A. riveri are re-described to include comparable morphological characteristics. The ecological implications of egg case morphology on oviposition and ventilation are also discussed. © 2007 Elsevier GmbH. All rights reserved., Cited By (since 1996):9, Fish and Fisheries, ,
Author: Flammang, Ebert, Cailliet
Date: 2007-01-01T00:00:00Z

Title: Breaking with tradition: Redefining measures for diet description with a case study of the Aleutian skate Bathyraja aleutica (Gilbert 1896),
Description: Characterization of fish diets from stomach content analysis commonly involves the calculation of multiple relative measures of prey quantity (%N,%W,%FO), and their combination in the standardized Index of Relative Importance (%IRI). Examining the underlying structure of dietary data matrices reveals interdependencies among diet measures, and obviates the advantageous use of underused prey-specific measures to diet characterization. With these interdependencies clearly realized as formal mathematical expressions, we proceed to isolate algebraically, the inherent bias in %IRI, and provide a correction for it by substituting traditional measures with prey-specific measures. The resultant new index, the Prey-Specific Index of Relative Importance (%PSIRI), is introduced and recommended to replace %IRI for its demonstrated more balanced treatment of the relative measures of prey quantity, and less erroneous behavior across taxonomic levels of identified prey. As a case study, %PSIRI was used to examine the diet of the Aleutian skate Bathyraja aleutica from specimens collected from three ecoregions of the northern Gulf of Alaska (GOA) continental shelf during June-September 2005-2007. Aleutian skate were found to primarily consume the commonly abundant benthic crustaceans, northern pink shrimp Pandalus eous and Tanner crab Chionoecetes bairdi, and secondarily consume various teleost fishes. Multivariate variance partitioning by Redundancy Analysis revealed spatially driven differences in the diet to be as influential as skate size, sex, and depth of capture. Euphausiids and other mid-water prey in the diet were strongly associated with the Shelikof Strait region during 2007 that may be explained by atypical marine climate conditions during that year. © 2011 Springer Science+Business Media B.V., Cited By (since 1996):2, Fish and Fisheries, CODEN: EBFID, ,
Author: Brown, Bizzarro, Cailliet, Ebert
Date: 2012-01-01T00:00:00Z

Title: Maturity, fecundity, and reproductive cycle of the spotted ratfish, Hydrolagus colliei,
Description: Size at maturity, fecundity, and reproductive periodicity were estimated for the spotted ratfish, Hydrolagus colliei (Lay and Bennett, 1839), off the coast of California, Oregon, and Washington. Maximum body size and size at median maturity were greater for females than males. Skeletal muscle concentrations of the steroid hormones testosterone (T) and estradiol (E 2) predicted similar, but slightly smaller sizes at maturity than the morphological criterion. Stage of maturity for males was estimated identically using internal organs or external secondary sexual characters, thus allowing non-lethal maturity assessments. Size at median maturity was greater north of Point Conception for females, and north of Cape Mendocino for males. Peak parturition occurred from May to October, with increased concentrations of E2 in skeletal muscle of females correlating with ovarian recrudescence during November to February. No significant seasonal trends in female T were apparent, but mean female 11-ketotestosterone (11KT) was 300% greater in April than any other month during the parturition season. There was a marginal evidence for increased number and size of ova with maternal size. Extrapolation of the hypothesized 6 to 8-month egg-laying season to observed mean parturition rates of captive specimens yielded an estimated annual fecundity of 19.5-28.9 egg cases. Differences in fecundity among higher taxonomic classifications of chondrichthyans were detected with chimaeriform fishes more fecund than lamniform, myliobatiform, squaliform, and rhinobatiform fishes, and less fecund than rajiform fishes. © 2008 Springer-Verlag., Cited By (since 1996):10, CODEN: MBIOA, ,
Author: Barnett, Earley, Ebert, Cailliet
Date: 2009-01-01T00:00:00Z

Title: Stable-isotope analysis of a deep-sea benthic-fish assemblage: Evidence of an enriched benthic food web,
Description: In this study, fishes and invertebrates collected from the continental slope (1000 m) of the eastern North Pacific Ocean were analysed using stable-isotope analysis (SIA). Resulting trophic positions (T P) were compared to known diets and habitats from the literature. Dual isotope plots indicated that most species groups (invertebrates and fishes) sorted as expected along the carbon and nitrogen axes, with less intraspecific variability than interspecific variability. Results also indicated an isotopically distinct benthic and pelagic food web, as the benthic food web was more enriched in both nitrogen and carbon isotopes. Trophic positions from SIA supported this finding, resulting in the assignment of fishes to different trophic positions from those expected based on published dietary information. These differences can be explained largely by the habitat of the prey and the percentage of the diet that was scavenged. A mixing model estimated dietary contributions of prey similar to those of the known diet of Bathyraja trachura from stomach-content analysis (SCA). Linear regressions indicated that trophic positions calculated from SIA and SCA, when plotted against B. trachura total length for 32 individuals, exhibited similar variation and patterns. Only the T P from SCA yielded significant results (stomach content: P < 0·05, stable isotope: P > 0·05). © 2012 The Authors. Journal of Fish Biology © 2012 The Fisheries Society of the British Isles., Cited By (since 1996):6, Fish and Fisheries, Ecology, CODEN: JFIBA, ,
Author: Boyle, Ebert, Cailliet
Date: 2012-01-01T00:00:00Z

Title: A comparison of age and growth of the Bering skate, Bathyraja interrupta (Gill and Townsend, 1897), from two Alaskan large marine ecosystems,
Description: The Bering skate, Bathyraja interrupta, is commonly found in both the Bering Sea and Gulf of Alaska, where skates are a regular bycatch in commercial long line and bottom trawl fisheries. This is the first study to examine the age and growth of B. interrupta, and one of the few studies to directly compare growth parameters of a skate species between management regions. Ages were estimated based on band counts using the standard gross-sectioning method of vertebral centra preparation. Additionally, a preliminary investigation was conducted into the utility of the histological method. Several growth models were compared and the best-fit model for both regions was identified as the logistic model using the Akaike's Information Criterion approach. No significant difference was detected between sexes for any model in either region; however, a slight but significant difference was found between regions. The parameters of the logistic growth model based on the gross-sectioned preparation were L∞=82.80cm TL and k-1yr=0.23 for the eastern Bering Sea and L∞=86.94cm TL and k-1yr=0.20 for the Gulf of Alaska. Age estimates from the gross sectioned vertebral centra provided a minimum longevity of 19 years and 21 years, respectively. Estimates based on the histologically prepared samples provide overall slightly higher age estimates, but the same maximum age of 21 years. © 2014 Elsevier B.V., , ,
Author: Ainsley, Ebert, Natanson, Cailliet
Date: 2014-01-01T00:00:00Z

Title: Evidence of stability in a chondrichthyan population,
Description: Results presented here provide evidence of an exception to the generalization that all chondrichthyan populations are especially vulnerable to exploitation to the extent that they remain at low abundance for a protracted or indefinite duration even after exploitation rates are reduced. Delta log-normal generalized linear models (GLM) and cluster analysis of fishery-independent catch-per-unit-effort (CPUE) data from 1977 to 2006 indicated the presence of at least two distinct stocks of spotted ratfish Hydrolagus colliei off the U.S. West Coast. CPUE of the continental slope and northern continental shelf and upper slope populations did not vary between 1977 and 1995 and increased from 1995 to 2006. On the basis of the timing of these changes, it is likely that both fishing and climate influenced these trends. Sex and size-specific differences in bathymetric distribution, along with the identification of nursery sites, indicate that fishery by-catch could have a significant effect on population growth. These aggregative behaviours, combined with low fecundity, indicate that H. colliei may be vulnerable to irreversible population depletion by fisheries mortality. Temporal abundance trends indicated, however, that their population size has increased significantly within the last decade, a demonstration of population stability. A literature review indicated that there is also evidence for population stability in other chondrichthyans. The paradigm that all chondrichthyan populations fail to rebuild in response to exploitation, therefore, may not be as broadly applicable as previously thought. Thus, it is not necessarily sufficient to make generalizations regarding the vulnerability of chondrichthyans across higher taxonomic scales. © 2012 The Authors. Journal of Fish Biology © 2012 The Fisheries Society of the British Isles., Cited By (since 1996):1, Fish and Fisheries, CODEN: JFIBA, ,
Author: Barnett, Ebert, Cailliet
Date: 2012-01-01T00:00:00Z

Title: Comparative age and growth of the Aleutian skate, Bathyraja aleutica, from the eastern Bering Sea and Gulf of Alaska
Description: The Aleutian skate (Bathyraja aleutica) is a large deep-water species that commonly occurs in bycatch of Alaskan trawl and longline fisheries. Although prominent in the skate biomass of the eastern Bering Sea (EBS) and Gulf of Alaska (GOA) ecosystems, minimal biological information exists. To increase our understanding of this potentially vulnerable species, and address the possibility of two separate populations in Alaskan waters, the age and growth of B. aleutica was studied. Vertebral centra were examined for age determination, and multiple growth models were evaluated to determine growth characteristics. Skates from the EBS attained maximum ages of 17 and 16 years for females and males, respectively, and the two-parameter von Bertalanffy growth functions generated estimates of k = 0.13 yr.-1 and L∞ = 162.1 cm for females, with similar results for males. Skates from the GOA reached 19 years in females and 18 years in males. Growth parameters of female skates from the GOA were estimated as k = 0.11 yr.-1 and L∞ = 160.0 cm, whereas males grew faster, with estimates of k = 0.15 yr.-1 and L∞ = 138.2 cm. The results of this study may indicate the presence of distinct populations of B. aleutica in the eastern North Pacific.
Author: Haas, Ebert, Cailliet

Title: Assessment of the dorsal fin spine for chimaeroid (Holocephali: Chimaeriformes) age estimation,
Description: Previous attempts to age chimaeroids have not rigorously tested assumptions of dorsal fin spine growth dynamics. Here, novel imaging and data-analysis techniques revealed that the dorsal fin spine of the spotted ratfish Hydrolagus colliei is an unreliable structure for age estimation. Variation among individuals in the relationship between spine width and distance from the spine tip indicated that the technique of transverse sectioning may impart imprecision and bias to age estimates. The number of growth-band pairs observed by light microscopy in the inner dentine layer was not a good predictor of body size. Mineral density gradients, indicative of growth zones, were absent in the dorsal fin spine of H. colliei, decreasing the likelihood that the bands observed by light microscopy represent a record of growth with consistent periodicity. These results indicate that the hypothesis of aseasonal growth remains plausible and it should not be assumed that chimaeroid age is quantifiable by standard techniques. © 2009 The Fisheries Society of the British Isles., Cited By (since 1996):2, Fish and Fisheries, CODEN: JFIBA, ,
Author: Barnett, Ebert, Cailliet
Date: 2009-01-01T00:00:00Z

Title: Age and growth characteristics of the Starry Skate, Raja stellulata, with a description of life history and habitat trends of the central California, U.S.A., skate assemblage
Description: Skates are prevalent in fisheries worldwide, but rarely are they identified to species. This is of conservation and management concern since skates exhibit a broad range of life history characteristics. The present study investigated the age and growth of the Starry Skate, Raja stellulata, and compared it to other regional skates inhabiting the U.S. West Coast. Age and growth parameters were determined using two vertebral preparation techniques: gross sectioning and histological sectioning. Gross section age estimates ranged from zero to 11 years and growth was described by the two parameter von Bertalanffy growth function (2 VBGF; L ∞ = 915 mm total length (TL) and k = 0.13 year-1; n = 189). Histological section age estimates ranged from zero to 15 years and growth was also described by the 2 VBGF (L ∞ = 1092 mm TL, k = 0.06 year-1; n = 68). Histological section results reflect a more conservative life history, specifically a lower von Bertalanffy growth coefficient, but had slightly biased results and a smaller sample size than the gross section results. An age and depth trend was found within the central California skate assemblage, in which habitat depth and maximum age were positively correlated. © 2013 Springer Science+Business Media Dordrecht., Fish and Fisheries
Author: James, Ebert, Natanson, Cailliet
Date: 2014-01-01T00:00:00Z

Title: Age and growth of the roughtail skate Bathyraja trachura (Gilbert 1892) from the eastern North Pacific,
Description: This study provides the first published age estimates for the roughtail skate, Bathyraja trachura. Age and growth characteristics of B. trachura, a poorly-known deepwater species, were determined from samples collected along the continental slope of the contiguous western United States. A new maximum size was established at 91.0 cm TL. Age was determined using a traditional structure (vertebral thin sections) with widespread application on multiple skate species and a non-lethal structure (caudal thorns) recently used for age analysis on skate species. Caudal thorns were determined not to be a useful ageing structure for this species based on poor precision and significantly lower age estimates when compared to age estimates from vertebral thin sections. The best model for describing growth of B. trachura was the two parameter VBGF, assuming annual vertebral band deposition and using length-at-age data. Although females grew slower and reached a larger maximum size than males, their growth was not statistically different (ARSS; P = 0.90); therefore, data were pooled (L ∞ = 99.38, k = 0.09). Annual band deposition was found to be a reasonable assumption for this species, but has yet to be validated. The maximum age estimated for B. trachura was 20 years for males and 17 years for females using vertebral thin sections. © 2007 Springer Science+Business Media, Inc., Cited By (since 1996):9, Fish and Fisheries, CODEN: EBFID, ,
Author: Davis, Cailliet, Ebert
Date: 2007-01-01T00:00:00Z