Distribution Of Demersal Fishes Research Articles

Local size structure and distribution of demersal fish in relation to sea pens and other benthic habitats in a deep-sea soft-bottom environment

Many fish species undergo ontogenetic habitat shifts as they grow to fulfill new biological, ecological and environmental requirements. While relationships between fishes and large hard-substrate cold-water corals (CWC) (e.g., Desmophyllum pertusum reefs) have frequently been studied, there are relatively fewer studies examining the relationships of fish with habitats specifically provided by smaller corals (e.g., sea pens) in soft-bottom environments. Despite this knowledge gap around soft-bottom corals, growing evidence of their importance has nonetheless justified their inclusion as conservation targets in numerous Marine Protected Areas (MPA), including the Canadian Laurentian Channel MPA. Here, we performed ROV and near-seabed drift-camera system surveys within the Laurentian Channel MPA in 2017 and 2018 to assess the influence of fish body size and habitat type on fish small-scale distribution in a low-relief deep-sea soft-sediment environment. We compared the local size structure of the four most abundant deep-sea demersal fish taxa of the channel (Redfish (Sebastes spp.), Witch Flounder (Glyptocephalus cynoglossus), Marlin-Spike Grenadier (Nezumia bairdii) and Longfin Hake (Phycis chesteri)) across one barren and five structural benthic habitats defined by the presence of nine dominant epibenthic invertebrates (actiniarians and CWCs). We used generalized additive models to identify biotic (benthic habitats) and abiotic (depth, bottom types) covariates of size for each taxon. We observed 15,381 fish within the 43.6-ha study area, of which 7,511 fish were measured. Juveniles represented 99% of all fish measured, with a notable increase in average fish size in 2018. While we did not find any associations between benthic habitats and fish life stages, the analysis revealed a significant increase in fish size within sea pen habitats for all four taxa. Conversely, we found a taxon-specific influence of bottom type on fish size for all taxa. In addition, Redfish and Longfin Hake size was positively correlated with depth. For deep-sea demersal fish taxa of the MPA, our results suggest that 1) sea pens provide nursery habitat for early-life stages, 2) fish undergo ontogenetic shifts in micro-habitat use and specialization, and 3) fish-habitat associations appear to be facultative rather than obligate. Through the use of in-situ video data, this study provided evidence that small and large fish do not use the same micro-habitats, and that sea pens contribute significantly to fish habitat despite providing less habitat heterogeneity than reef-forming scleractinians or large gorgonians. These results contribute to empirical understanding of fish-habitat relationships at different fish life stages and may inform fisheries management, as well as monitoring efforts in the MPA and other protected deep-sea environments.

Habitat and morphological characteristics affect juvenile mortality in five coral reef damselfishes

The abundance and distribution of demersal fishes rely on larvae successfully settling from the pelagic environment to a benthic habitat and their subsequent survival. With high mortality rates during this life stage, settling to a habitat that maximizes survival is critical. However, relationships between settlement choices and subsequent survival are poorly understood and may vary among species with different habitat preferences. To test this, we focused on five congeneric (Pomacentrus) damselfish species that are known to differ in their habitat choices and explored whether habitat associations at settlement influenced survival. Newly settled individuals were tagged and monitored daily for two weeks to estimate natural mortality rates. Morphological attributes of fish and characteristics of settlement habitats, including depth, rugosity, benthic substrata, and local fish assemblages, were used to predict mortality. We found that some species displayed stronger associations with specific benthic substrata at settlement, but contrary to expectations, these selected habitat characteristics were relatively weak predictors of survivorship. Our survival analysis revealed that the best predictors of survivorship were rugosity (P. adelus and P. amboinensis) and two morphological traits, body depth and ocellus size (P. chrysurus and P. adelus). Interestingly, we found that P. moluccensis that settled in areas of high coverage of mounding coral experienced increased mortality. Of the remaining substrata, analysis showed that instead of associating with habitat characteristics enhancing survivorship, individuals tended not to associate with habitats characteristics that increased mortality (e.g., Turbinaria and sand). This study highlights the species-specific drivers of early post-settlement mortality in coral reef fishes.

Discrete seafloor features associated with juvenile haddock (Melanogrammus aeglefinus): A coarse-graining approach for identifying habitat scale

Ecological patterns and processes occur at a myriad of spatial and temporal scales. Determining the appropriate scale(s) to collect and analyze data depends on the phenomena being studied and no one scale is appropriate for all of these. Knowing relevant measurement scales avoids the risk of presenting results that are merely a function of measurement scale rather than those relevant to actual ecological processes. Attribution of patterns to ecological processes requires a means to measure and evaluate these patterns. We present a standardized method to determine relevant spatial scales of fish-habitat associations observed from linear transect data on juvenile haddock (Melanogrammus aeglefinus), collected from six sites on the Scotian Shelf, off Canada's eastern coast. The survey data came from a large spatial scale research project undertaken by Fisheries and Oceans Canada to investigate spatial distribution of demersal fish in relation to seabed habitat in 2002 and 2003. We examined the relationship between two elements of this extensive dataset – the “towcam” video survey of demersal fish, and the interpreted surficial geology maps derived from sidescan sonar. We used the data from these surveys (48 towcam survey transect lines; 6 study sites, 2 5-km transect lines per site, day and night surveys per line, in each of 2 years = 240 km of transects), superimposed on the interpreted surficial geology layer collected at the same time. The resolution of the observations (∼2.5 m) facilitated a detailed examination of the spatial scales of juvenile haddock association with seabed habitat. This was achieved using a “coarse-graining” approach, which we applied by summarizing fish abundance and seabed habitat proportions across bin sizes starting at 5 m and progressively doubling to 640 m. We tallied significant correlations by bin size to observe patterns in fish-habitat associations as a function of measurement scale, for each age group and diel period. We found that Juvenile haddock-seabed associations deteriorated at the grain limits marking the range of spatial scaling relevant for this phenomenon. We present a robust approach for quantifying appropriate scales of aggregations across linear transects which can serve as an important tool for basing observations to describe ecological patterns in space.

Modelling the variation of demersal fish distribution in Yellow Sea under climate change

Modelling the variation of demersal fish distribution in Yellow Sea under climate change

The use of singlebeam echo-sounder depth data to produce demersal fish distribution models that are comparable to models produced using multibeam echo-sounder depth.

Seafloor characteristics can help in the prediction of fish distribution, which is required for fisheries and conservation management. Despite this, only 5%–10% of the world's seafloor has been mapped at high resolution, as it is a time‐consuming and expensive process. Multibeam echo‐sounders (MBES) can produce high‐resolution bathymetry and a broad swath coverage of the seafloor, but require greater financial and technical resources for operation and data analysis than singlebeam echo‐sounders (SBES). In contrast, SBES provide comparatively limited spatial coverage, as only a single measurement is made from directly under the vessel. Thus, producing a continuous map requires interpolation to fill gaps between transects. This study assesses the performance of demersal fish species distribution models by comparing those derived from interpolated SBES data with full‐coverage MBES distribution models. A Random Forest classifier was used to model the distribution of Abalistes stellatus, Gymnocranius grandoculis, Lagocephalus sceleratus, Loxodon macrorhinus, Pristipomoides multidens, and Pristipomoides typus, with depth and depth derivatives (slope, aspect, standard deviation of depth, terrain ruggedness index, mean curvature, and topographic position index) as explanatory variables. The results indicated that distribution models for A. stellatus, G. grandoculis, L. sceleratus, and L. macrorhinus performed poorly for MBES and SBES data with area under the receiver operator curves (AUC) below 0.7. Consequently, the distribution of these species could not be predicted by seafloor characteristics produced from either echo‐sounder type. Distribution models for P. multidens and P. typus performed well for MBES and the SBES data with an AUC above 0.8. Depth was the most important variable explaining the distribution of P. multidens and P. typus in both MBES and SBES models. While further research is needed, this study shows that in resource‐limited scenarios, SBES can produce comparable results to MBES for use in demersal fish management and conservation.

Testing the Improvement of Coral Reef Associated Fish Distribution Models Based on Multibeam Bathymetry by Adding Seafloor Backscatter Data

Demersal fishes constitute an essential component of the continental shelf ecosystem, and a significant element of fisheries catch around the world. However, collecting distribution and abundance data of demersal fish, necessary for their conservation and management, is usually expensive and logistically complex. The increasing availability of seafloor mapping technologies has led to the opportunity to exploit the strong relationship demersal fish exhibit with seafloor morphology to model their distribution. Multibeam echo-sounder (MBES) systems are a standard method to map seafloor morphology. The amount of acoustic energy reflected by the seafloor (backscatter) is used to estimate specific characteristics of the seafloor, including acoustic hardness and roughness. MBES data including bathymetry and depth derivatives were used to model the distribution of Abalistes stellatus, Gymnocranius grandoculis, Lagocephalus sceleratus, Lethrinus miniatus, Loxodon macrorhinus, Lutjanus sebae, and Scomberomorus queenslandicus. The possible improvement of model accuracy by adding the seafloor backscatter was tested in three different areas of the Ningaloo Marine Park off the west coast of Australia. For the majority of species, depth was a primary variable explaining their distribution in the three study sites. Backscatter was identified to be an important variable in the models, but did not necessarily lead to a significant improvement in the demersal fish distribution models’ accuracy. Possible reasons for this include: the depth and derivatives were capturing the significant changes in the habitat, or the acoustic data collected with a high-frequency MBES were not capturing accurately relevant seafloor characteristics associated with the species distribution. The improvement in the accuracy of the models for certain species using data already available is an encouraging result, which can have a direct impact in our ability to monitor these species.

Tingkat pemanfaatan ikan kaci-kaci (<em>Diagramma pictum</em>) pada perairan Mapur yang didaratkan di Desa Kelong, Kabupaten Bintan, Indonesia

Mapur waters is one of the potential areas for demersal fish distribution in Bintan waters. The purpose of this study was to investigate the effort of catching painted sweetlips fish (Diagramma pictum), Maximum Sustainable Yield of Painted Sweetlips Fish and investigated the amount of Painted Sweetlips Fish catches allowed (JTB). The research method used is the survey method, which is direct observation at the research location by recording fishing operations such as fishing gear and catches through direct interviews with fishermen working in fish storage warehouses. Data taken in the form of primary data and secondary data. The results showed that the effort of catching Painted Sweetlips Fish on Mapur waters was 314.00 units, with the MSY value was 713,016 kg/unit. So that the amount of catch allowed (JTB) is 80% from MSY which is equal to 570.41 kg/unit, with the utilization rate of Painted Sweetlips Fish on which is equal to 89%.

DISTRIBUTION AND DENSITY OF DEMERSAL FISHES IN YOUTEFA BAY, PAPUA, INDONESIA: A STUDY USING HYDROACOUSTIC TECHNOLOGY

A study was conducted to estimate the distribution and density of demersal fish in Youtefa Bay, Papua, Indonesia, using hydroacoustic technology. The hydroacoustic survey was carried out using a single beam echosounder SIMRAD EK-15 which operates at a frequency of 200 kHz. The hydroacoustic data was processed using Echoview software with a threshold between -70.00 to -34.00 dB. Schooling fish were detected at a maximum distance of 3 m from the seabed, with average volume backscattering strength ranging between -60.13 and -42.01 dB. The demersal fish density in the Youtefa Bay ranged from 0.09 to 42.19 fish m-3 with an average density of 12.62 fish m-3. The schools of demersal fish were dominantly detected in the coastal waters of Enggros Village to Abe Pantai Village. The condition of substrate and water depth seems to influence the spatial and vertical distribution of demersal fish in the Youtefa Bay.

Vertical stratification in the distribution of demersal fishes along the walls of the La Jolla and Scripps submarine canyons, California, USA

The geographic distributions of many coastal marine fish assemblages are strongly driven by habitat features, particularly among demersal fishes that live along the seafloor. Ecologists have long recognized the importance of characterizing fish habitat associations, especially where spatial management is under consideration. However, little is known about fish distributions and habitat suitability in unique demersal habitats such as submarine canyons. The active continental margin of the California coast is cut by eight submarine canyons, several of which extend from the shore to the deep abyssal plain. We sampled the demersal fish assemblages in two of those canyons: (1) the Scripps submarine canyon in the San-Diego-Scripps State Marine Conservation Area (SMCA) and (2) the La Jolla canyon in the Matlahuayl State Marine Reserve (SMR) to gain insight into both the distributions and habitat associations of demersal fishes in canyons. A remotely operated vehicle was used to conduct 21 vertically oriented transects along the canyon walls in depths ranging from 20 to 300m. Species composition was assessed in three depth-stratified zones (100m per zone) along the canyon walls. Species richness, abundance, and attributes of the surrounding canyon habitat structure (slope and benthic terrain ruggedness) were quantified. Three distinct assemblage groupings were identified, which comprised 35 species of demersal fishes from 17 families. Among all factors analyzed in this study, depth, slope, and ruggedness were strong explanatory variables of patterns of species richness and abundance; however, the relationship between depth and assemblage structure was non-linear. The greatest number of species was observed in the mid depth-stratified zone. These trends suggest that variation in canyon dynamics across depth strata may facilitate distinct assemblage groupings of demersal fishes, which can in turn be used to better manage these unique habitats.

Demersal fish communities of the shelf and slope of South Georgia and Shag Rocks (Southern Ocean)

This research is the first to investigate deepwater demersal fish distribution and community structure around South Georgia and Shag Rocks. Analysis of catch data from a trawl survey conducted in 2003 indicated that depth and location have a marked influence over demersal fish community structure in the region. Three distinct, depth-stratified fish assemblages were observed. The demersal fish assemblage found on the shelf to depths of around 400 m was dominated by nototheniids and was comprised largely of species endemic to the Southern Ocean and Scotia Sea. At the greatest depths sampled (>600 m) the demersal fish community was dominated by gadiform fishes including members of the Macrouridae and Moridae, many of which are not endemic to the Southern Ocean. From 400 to 600 m there was a transitional zone with demersal fish representatives of both the shelf and deeper slope communities. Clear geographic differences in the shelf community were apparent with differences observed in community structure between South Georgia and Shag Rocks to depths of around 400 m. These data provide valuable baseline information to aid environmental management decisions and assess potential impacts of rapid ocean warming around South Georgia.

Exploring diversity and distribution of demersal fish species from the Northern Alboran Sea and Gulf of Vera (Western Mediterranean Sea)

Exploring diversity and distribution of demersal fish species from the Northern Alboran Sea and Gulf of Vera (Western Mediterranean Sea)

Demersal fish distribution and habitat use within and near Baltimore and Norfolk Canyons, U.S. middle Atlantic slope

Numerous submarine canyons along the United States middle Atlantic continental margin support enhanced productivity, diverse and unique habitats, active fisheries, and are vulnerable to various anthropogenic disturbances. During two cruises (15 Aug–2 Oct 2012 and 30 Apr–27 May 2013), Baltimore and Norfolk canyons and nearby areas (including two cold seeps) were intensively surveyed to determine demersal fish distributions and habitat associations. Overall, 34 ROV dives (234–1612m) resulted in 295h of bottom video observations and numerous collections. These data were supplemented by 40, 30-min bottom trawl samples. Fish observations were assigned to five general habitat designations: 1) sand-mud (flat), 2) sloping sand-mud with burrows, 3) low profile gravel, rock, boulder, 4) high profile, canyon walls, rocks or ridges, and 5) seep-mixed hard and soft substrata, the later subdivided into seven habitats based on amounts of dead mussel and rock cover. The influence of corals, sponges and live mussels (seeps only) on fish distributions was also investigated. Both canyon areas supported abundant and diverse fish communities and exhibited a wide range of habitats, including extensive areas of deep-sea corals and sponges and two nearby methane seeps (380–430m, 1455–1610m). All methods combined yielded a total of 123 species of fishes, 12 of which are either new records for this region or have new range data. Depth was a major factor that separated the fish faunas into two zones with a boundary around 1400m. Fishes defining the deeper zone included Lycodes sp., Dicrolene introniger, Gaidropsaurus ensis, Hydrolagus affinis, Antimora rostrata, and Aldrovandia sp. Fishes in the deep zone did not exhibit strong habitat affinities, despite the presence of a quite rugged, extensive methane seep. We propose that habitat specificity decreases with increasing depth. Fishes in the shallower zone, characterized by Laemonema sp., Phycis chesteri, Nezumia bairdii, Brosme brosme, and Helicolenus dactylopterus, exhibited a variety of habitat use patterns. In general, fish assemblages in the soft substrata areas (dominated by P. chesteri, N. bairdii, Glyptocephalus cynoglossus, Lophius americanus, Merluccius albidus) were different from those in more complex habitats (dominated by Laemonema spp., Hoplostethus spp., B. brosme, Benthocometes robustus, L. americanus, Dysommina rugosa). Although, when present, the dense coral and sponge cover did not statistically affect general fish assemblage patterns in hard bottom habitats, these sessile organisms markedly increased habitat complexity, and some fish species exhibited close association with them. Fish species compositions in the two canyons were not substantially different from the surrounding slopes. However, the diversity of habitats within both the canyons and seeps exerted an important influence on assemblage structure. At least for some species (e.g., B. brosme) canyon and seep environments may be a refuge from intensive bottom fishing activities. We frequently observed evidence of commercial and recreational fishing activity (lost gear on bottom and fishing boats in the area) throughout the canyons and some resulting habitat damage. Conservation measures for the unique and more vulnerable areas (seep and coral habitats) have recently been approved.

Effects of climate on temporal variation in the abundance and distribution of the demersal fish assemblage in the Tsushima Warm Current region of the Japan Sea

AbstractIn the present study, we examined the effects of climate on temporal variation in the abundance and geographical distribution of demersal fishes at both interannual and decadal scales in the Tsushima Warm Current region of the Japan Sea using single‐trawler fishery data (1972–2002). This single‐trawler fishery targeted multiple species with different geographical affinities and life history traits. Thus, these data were suitable for examining the biological mechanisms that underlie how species respond to climate variability. Our results indicate that the distributional changes of species in response to decadal climate variability are best explained by asymptotic length, which indicates that warming has greater negative effects on larger fishes in the Japan Sea. However, none of the variables examined (including geographical affinity, asymptotic length and age at maturation) could explain the shift in abundance at interannual or decadal scales. It should be noted that life history traits and geographical affinities only provide partial explanations of the responses of species to environmental variability, thereby suggesting that other factors, such as interactions among species, may be involved in mediating species responses.

Influence of structurally complex benthic habitats on fish distribution

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 520:175-190 (2015) - DOI: https://doi.org/10.3354/meps11047 Influence of structurally complex benthic habitats on fish distribution Tina Kutti1,*, Jan Helge Fosså1, Odd Aksel Bergstad2 1Institute of Marine Research, PO Box 1870, Nordnes, 5817 Bergen, Norway 2Institute of Marine Research, Flødevigen, 4817 His, Norway *Corresponding author: tina.kutti@imr.no ABSTRACT: This study examined the relationship between demersal fish distributions and benthic habitats in the Trænadjupet marine protected area (MPA) on the Norwegian continental shelf. Using a towed video system, multiple pairs of plots with varying densities of cold-water coral mounds and sponges were examined, as well as control plots containing neither of these taxa. A total area of 130000 m2 was surveyed along 16 and 12 linear transects in 2009 and 2010 respectively. The most numerous demersal fish were Sebastes viviparus and Trisopterus esmarkii, followed by Brosme brosme, Chimaera monstrosa and Micromesistius poutassou. Analyses indicated that T. esmarkii and M. poutassou exhibited very general patterns of habitat selection whereas C. monstrosa, S. viviparus and B. brosme appeared to be more specialized in their selection of habitat. C. monstrosa was abundant in the sponge-beds and unstructured seabed, and appeared only rarely in the coral habitats. The occurrence of cold-water coral mounds and sponges seemed to mainly influence the distribution of S. viviparus and B. brosme, which were twice as abundant in areas with structurally complex sponge and coral habitats than in the unstructured flat seabed at all spatial scales examined (i.e. <3 m to 2 km). None of the fish species examined in Trænadjupet were confined to only one of the habitats examined, thus the study confirmed facultative use of cold-water corals and sponges as fish habitats on the Norwegian continental shelf. KEY WORDS: NE Atlantic · Sponge grounds · Cold-water corals · Demersal fish · Habitat association · Sebastes viviparus · Brosme brosme · Lophelia pertusa Full text in pdf format PreviousNextCite this article as: Kutti T, Fosså JH, Bergstad OA (2015) Influence of structurally complex benthic habitats on fish distribution. Mar Ecol Prog Ser 520:175-190. https://doi.org/10.3354/meps11047 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 520. Online publication date: February 03, 2015 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2015 Inter-Research.

The importance of deep-sea vulnerable marine ecosystems for demersal fish in the Azores

Cold-water corals and sponges aggregations are important features of the deep sea, recently classified as vulnerable marine ecosystems (VMEs). VMEs increase habitat complexity, believed to act as feeding, reproductive, nursery and refuge areas for a high number of invertebrates and fish species. In the Azores archipelago (NE Atlantic), VMEs are prevalent but their ecological role has not received much attention. The objective of this study was to investigate the importance of VMEs in influencing the distribution of demersal fish in the Azores. With data collected during experimental longline surveys , we modeled the catch of six demersal fish species of commercial value (Helicolenus dactylopterus, Pagellus bogaraveo, Mora moro, Conger conger, Phycis phycis, Pontinus kuhlii) in relation to the presence of VMEs and other environmental factors using General Additive Models (GAMs). Our study demonstrated that total fish catch was higher inside VMEs but the relationship between fish and VMEs varied among fish species. Species specific models showed that catch was strongly influenced by environmental factors, mainly depth, whilst the presence of VMEs was only important for two rockfish species; juvenile and adult P. kuhlii and juvenile H. dactylopterus. Although the association between deep-sea demersal fish and VMEs may be an exception to the rule, we suggest that VMEs act as an important habitat for two commercially important species in the Azores.

Distribution of demersal fishes along the US west coast (Canada to Mexico) in relation to spatial fishing closures (2003-2011)

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 501:169-190 (2014) - DOI: https://doi.org/10.3354/meps10674 Distribution of demersal fishes along the US west coast (Canada to Mexico) in relation to spatial fishing closures (2003-2011) Aimee A. Keller1,*, W. Waldo Wakefield2, Curt E. Whitmire2, Beth H. Horness1, Marlene A. Bellman1, Keith L. Bosley2 1Fishery Resource Analysis and Monitoring Division, Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 2725 Montlake Boulevard East, Seattle, Washington 98112, USA 2Fishery Resource Analysis and Monitoring Division, Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanographic and Atmospheric Administration, 2032 S. OSU Drive, Newport, Oregon 97365, USA *Corresponding author: aimee.keller@noaa.gov ABSTRACT: A temporally and spatially variable Rockfish Conservation Area (RCA) was established as a marine protected area along the US west coast in 2002 to protect stocks of rockfishes Sebastes spp. Since the RCA falls within the region sampled annually by the West Coast Groundfish Bottom Trawl Survey, we utilized data collected from 2003 to 2011 to evaluate whether establishment of the RCA influenced catch per unit effort (CPUE), species richness, and size distribution of demersal fishes. We compared CPUE and species richness among 3 management areas (continuously closed, periodically closed, and open to commercial bottom trawling) using analysis of covariance models that account for variability due to area, year, and depth. The most appropriate models for CPUE (35 species treated individually and aggregated into 6 subgroups) and species richness were selected using Akaike’s information criterion. All of the best-fit models were highly significant (p < 0.0001), explaining 3 to 76% of the variation in catch. For 27 species and 5 subgroups, mean CPUE was significantly greater within the area continuously closed to commercial bottom trawling relative to areas periodically closed or open. The most appropriate model for richness included area and year, and mean richness was greatest in the area continuously closed to trawling. Species-specific length composition distributions were calculated from subsampled individual lengths for 31 species. Significant differences in length frequency distributions were observed, with a higher proportion (~65%) of larger fish most often present in areas continuously closed to commercial bottom trawling (20 of 31 species) relative to other areas. Our data suggest that the RCA is an effective management tool for conserving not only rockfishes, but also other demersal fish species. KEY WORDS: California Current System · Demersal fishes · Spatial fisheries management · Rockfish Conservation Area Full text in pdf format PreviousNextCite this article as: Keller AA, Wakefield WW, Whitmire CE, Horness BH, Bellman MA, Bosley KL (2014) Distribution of demersal fishes along the US west coast (Canada to Mexico) in relation to spatial fishing closures (2003-2011). Mar Ecol Prog Ser 501:169-190. https://doi.org/10.3354/meps10674 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 501. Online publication date: March 31, 2014 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2014 Inter-Research.

Comparing large‐scale bioregions and fine‐scale community‐level biodiversity predictions from subtidal rocky reefs across south‐eastern Australia

Summary1. In the absence of knowledge of the large‐scale structure and distribution of marine biota, bioregionalisations, that is, spatial classifications of data on a range of environmental and/or biological attributes, are often viewed as one of the most appropriate frameworks within which to develop networks of marine protected areas (MPAs). However, despite their potential usefulness, few studies have assessed whether bioregionalisations can be used for management of species other than those it was derived from or whether bioregionalisations capture fully fine‐scale community‐level biodiversity patterns.2. We investigated the large‐scale structure and distribution of demersal fishes and macroinvertebrates in south‐eastern Australia, using rank abundance distributions (RADs). We used a recently developed community modelling method that allows their multivariate distribution to vary according to environmental gradients, assessing the congruency of mapped biogeographic patterns between the different taxa, and in the light of the Interim Marine and Coastal Regionalisation for Australia (IMCRA).3. A clear pattern in our analysis based on RADs showed a large difference in assemblage structure (i.e. in abundance, richness and evenness) between South Australia, where assemblages were generally more species rich and even, and Victoria and Tasmania, where assemblages were generally more species poor and uneven. The strong longitudinal pattern in species richness and evenness was generally congruent for both demersal fishes and macroinvertebrates and related to regional differences in oceanography.4. We found that the regions of highest species richness were found in the ‘core’ bioregions rather than ‘transition’ bioregions as defined in the IMCRA and for both taxa. Moreover, we found that not all assemblage structures were equally alike and that South Australia had the greatest range of unique assemblage structures.5. Synthesis and applications. While bioregionalisations are typically based on data from a single taxon, our findings highlight that they can be used as a surrogate for biological patterns seen in other taxa. Bioregionalisations, however, may not capture fully fine‐scale community‐level biodiversity patterns, and this may compromise the ability of protected area networks to protect the full variability in assemblage types. We suggest that it may be necessary to validate existing regionalisations with additional data and analyses such as the RAD analyses conducted here.

POTENSI DAN TINGKAT PEMANFAATAN SUMBERDAYA IKANDEMERSAL DI PERAIRAN KABUPATEN PEKALONGAN

ABSTRACT Pekalongan Regency seawaters is one of potential demersal fish distribution area. If resources utilization are uncontrol, the resources will be threatened by fishing effort increase. Information about potency and utilization rate should be known. This research purposes were to analyze potency of demersal fish, biological and economic aspects of demersal fish utilization in Pekalongan Regency seawaters that analyzed Catch per Unit Effort (CPUE), Maximum Sustainable Yield (MSY), Maximum Economic Yield (MEY), dan Open Access Equilibrium (OAE).This research conducted in Februari-April 2011. Research method was explorative survey. Sampling method was using purposive sampling with 36 samples obtained. Data that used in this research were primary and secondary data. Data analysis method used swept area and bioeconomic method – Gordon-Schaefer Model. This study showed that the demersal fish potency in Pekalongan Regency Seawaters was 36.16 metric tons. The average Catch per Unit Effort (CPUE) rate for 2001-2010 in Pekalongan Regency Seawaters was 0,055 metric tons/trip. The optimum catch (Copt) of the Maximum Sustainable Yield (MSY) was 880 metric tons per year with optimum effort (Eopt) 17.237 trip per year. The optimum catch (Copt) of the Maximum Economic Yield (MEY) was 735 metric tons per year with optimum effort (Eopt) was 10.236 trip per year. The optimum catch (Copt) of the Open Access Equilibrium (OAE) was 849 metric tons per year with optimum effort (Eopt) was 20.472 trip per year. The demersal fish resource utilization rate during the last 10 years in Pekalongan Regency has an average rating of 117%, which means that the demersal fish resource utilization rate was overfishing. Keywords: Demersal Fish Resource, Potency, Utilization Rate, Pekalongan Regency

Biophysical Factors Affecting the Distribution of Demersal Fish around the Head of a Submarine Canyon Off the Bonney Coast, South Australia

We sampled the demersal fish community of the Bonney Canyon, South Australia at depths (100–1,500 m) and locations that are poorly known. Seventy-eight species of demersal fish were obtained from 12 depth-stratified trawls along, and to either side, of the central canyon axis. Distributional patterns in species richness and biomass were highly correlated. Three fish assemblage groupings, characterised by small suites of species with narrow depth distributions, were identified on the shelf, upper slope and mid slope. The assemblage groupings were largely explained by depth (ρw = 0.78). Compared to the depth gradient, canyon-related effects are weak or occur at spatial or temporal scales not sampled in this study. A conceptual physical model displayed features consistent with the depth zonational patterns in fish, and also indicated that canyon upwelling can occur. The depth zonation of the fish assemblage was associated with the depth distribution of water masses in the area. Notably, the mid-slope community (1,000 m) coincided with a layer of Antarctic Intermediate Water, the upper slope community (500 m) resided within the core of the Flinders Current, and the shelf community was located in a well-mixed layer of surface water (<450 m depth).

Effect of prey abundance and size on the distribution of demersal fishes

Many demersal fish species rely on benthic prey as food sources for part of, or in some cases, all of their life history. We investigated the relationships between prey and predator abundance and prey size and predator mouth gape size for nine demersal fish species. Of the species analysed, four showed a significant positive increase in abundance with increasing prey abundance. Prey size is thought to be an important parameter for demersal fish that are limited in their feeding potential by their mouth gape size, as it influences consumption rate and energy expenditure while foraging. The relationship between prey size and mouth gape was investigated using both stomach content data and prey availability data. Stomach content analysis revealed positive relationships between maximum prey size and predator mouth gape size for six of the species. Indications of prey size selectivity were only seen in the environment for European hake ( Merluccius merluccius ), highlighting the potential importance of prey size over prey abundance for this species. The results demonstrate that prey abundance and size are of significance for some demersal fish species feeding primarily on benthos and will help in defining habitat requirements of demersal fish species.