Shortraker Rockfish, Sebastes borealis, Observed from a Manned Submersible

These are the first documented observations of shortraker rockfish, Sebastes borealis, in their natural habitat. The in situ observations were made from a manned submersible in 1991 in the eastern Gulf of Alaska. Eleven dives were completed from 207 to 357 m (679-1,171 feet); shortraker rockfish were observed during four dives. Their apparent indifference to the submersible allowed observations of their spatial distribution and habitat. The shortraker rockfish observed (20 total) were not schooled and were at least 50 m (164 feet) apart. Nineteen were on the bottom, and one was 0.5 m (20 inches) above the bottom. They were using 3-12° sloping terrain composed of either silt or pebbles interspersed with boulders (diameter 0.5-4.0 m (1.6-13 feet)); six were next to boulders.

Reactions of fishes to two underwater survey tools, a manned submersible and a remotely operated vehicle

We examined the reactions of fishes to a manned submersible and a remotely operated vehicle (ROV) during surveys conducted in habitats of rock and mud at depths of 30–408 m off central California in 2007. We observed 26 taxa for 10,550 fishes observed from the submersible and for 16,158 fishes observed from the ROV. A reaction was defined as a distinct movement of a fish that, for a benthic or hovering individual, was greater than one body length away from its initial position or, for a swimming individual, was a change of course or speed. Of the observed fishes, 57% reacted to the ROV and 11% reacted to the submersible. Aggregating species and those species initially observed off the seafloor reacted most often to both vehicles. Fishes reacted more often to each vehicle when they were >1 m above the seafloor (22% of all fishes >1 m above the seafloor reacted to the submersible and 73% to the ROV) than when they were in contact with the seafloor (2% of all reactions to the submersible and 18% to the ROV). Fishes reacted by swimming away from both vehicles rather than toward them. Consideration of these reactions can inform survey designs and selection of survey tools and can, thereby, increase the reliability of fish assemblage metrics (e.g., abundance, density, and biomass) and assessments of fish and habitat associations.

Integration of submersible transect data and high-resolution multibeam sonar imagery for a habitat-based groundfish assessment of Heceta Bank, Oregon

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 in this 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.

Biogeographic analysis of the Tortugas Ecological Reserve: Examining the refuge effect following reserve establishment

Almost 120 days at sea aboard three NOAA research vessels and one fishing vessel over the past three years have supported biogeographic characterization of Tortugas Ecological Reserve (TER). This work initiated measurement of post-implementation effects of TER as a refuge for exploited species. In Tortugas South, seafloor transect surveys were conducted using divers, towed operated vehicles (TOV), remotely operated vehicles (ROV), various sonar platforms, and the Deepworker manned submersible. ARGOS drifter releases, satellite imagery, ichthyoplankton surveys, sea surface temperature, and diver census were combined to elucidate potential dispersal of fish spawning in this environment. Surveys are being compiled into a GIS to allow resource managers to gauge benthic resource status and distribution. Drifter studies have determined that within the ~ 30 days of larval life stage for fishes spawning at Tortugas South, larvae could reach as far downstream as Tampa Bay on the west Florida coast and Cape Canaveral on the east coast. Together with actual fish surveys and water mass delineation, this work demonstrates that the refuge status of this area endows it with tremendous downstream spillover and larval export potential for Florida reef habitats and promotes the maintenance of their fish communities. In Tortugas North, 30 randomly selected, permanent stations were established. Five stations were assigned to each of the following six areas: within Dry Tortugas National Park, falling north of the prevailing currents (Park North); within Dry Tortugas National Park, falling south of the prevailing currents (Park South); within the Ecological Reserve falling north of the prevailing currents (Reserve North); within the Ecological Reserve falling south of the prevailing currents (Reserve South); within areas immediately adjacent to these two strata, falling north of the prevailing currents (Out North); and within areas immediately adjacent to these two strata, falling south of the prevailing currents (Out South). Intensive characterization of these sites was conducted using multiple sonar techniques, TOV, ROV, diver-based digital video collection, diver-based fish census, towed fish capture, sediment particle-size, benthic chlorophyll analyses, and stable isotope analyses of primary producers, fish, and, shellfish. In order to complement and extend information from studies focused on the coral reef, we have targeted the ecotone between the reef and adjacent, non-reef habitats as these areas are well-known in ecology for indicating changes in trophic relationships at the ecosystem scale. Such trophic changes are hypothesized to occur as top-down control of the system grows with protection of piscivorous fishes. Preliminary isotope data, in conjunction with our prior results from the west Florida shelf, suggest that the shallow water benthic habitats surrounding the coral reefs of TER will prove to be the source of a significant amount of the primary production ultimately fueling fish production throughout TER and downstream throughout the range of larval fish dispersal. Therefore, the status and influence of the previously neglected, non-reef habitat within the refuge (comprising ~70% of TER) appears to be intimately tied to the health of the coral reef community proper. These data, collected in a biogeographic context, employing an integrated Before-After Control Impact design at multiple spatial scales, leave us poised to document and quantify the postimplementation effects of TER. Combined with the work at Tortugas South, this project represents a multi-disciplinary effort of sometimes disparate disciplines (fishery oceanography, benthic ecology, food web analysis, remote sensing/geography/landscape ecology, and resource management) and approaches (physical, biological, ecological). We expect the continuation of this effort to yield critical information for the management of TER and the evaluation of protected areas as a refuge for exploited species. (PDF contains 32 pages.)

Demersal groundfish densities in trawlable and untrawlable habitats off Washington: implications for the estimation of habitat bias in trawl surveys

Demersal groundfish densities were estimated by conducting a visual strip-transect survey via manned submersible on the continental shelf off Cape Flattery, Washington. The purpose of this study was to evaluate the statistical sampling power of the submersible survey as a tool to discriminate density differences between trawlable and untrawlable habitats. A geophysical map of the study area was prepared with side-scan sonar imagery, multibeam bathymetry data, and known locations of historical NMFS trawl survey events. Submersible transects were completed at randomly selected dive sites located in each habitat type. Significant differences in density between habitats were observed for lingcod (Ophiodon elongatus), yelloweye rockfish (Sebastes ruberrimus), and tiger rockfish (S. nigrocinctus) individually, and for “all rockfish” and “all flatfish” in the aggregate. Flatfish were more than ten times as abundant in the trawlable habitat samples than in the untrawlable samples, whereas rockfish as a group were over three times as abundant in the untrawlable habitat samples. Guidelines for sample sizes and implications for the estimation of the continental shelf trawl-survey habitat-bias are considered. We demonstrate an approach that can be used to establish sample size guidelines for future work by illustrating the interplay between statistical sampling power and 1) habitat specific-density differences, 2) variance of density differences, and 3) the proportion of untrawlable area in a habitat.

Deep reef fish surveys by submersible on Alderdice, McGrail, and Sonnier Banks in the Northwestern Gulf of Mexico

Submersible surveys at numerous reefs and banks in the northwestern Gulf of Mexico (NWGOM) were conducted as part of the Sustainable Seas Expedition (SSE) during July/August 2002 to identify reef fish communities, characterize benthic habitats, and identify deep coral reef ecosystems. To identify the spatial extent of hard bottom reef communities, the Flower Garden Banks National Marine Sanctuary (FGBNMS) and the U.S. Geological Survey (USGS) mapped approximately 2000 km2 of the Northwestern Gulf of Mexico (NWGOM) continental shelf during June 2002 with high-resolution multibeam bathymetry. Previous investigations conducted on the features of interest (with the exceptions of East and West Flower Garden and Sonnier Banks, accessible by SCUBA) had not been conducted since the 1970s and 1980s, and did not have the use of high-resolution maps to target survey sites. The base maps were instrumental in navigating submersibles to specific features at each study site during the Sustainable Seas Expedition (SSE)—a submersible effort culminating from a partnership between the National Atmospheric and Oceanic Administration (NOAA) and the National Geographic Society (NGS). We report the initial findings of our submersible surveys, including habitat and reef fish diversity at McGrail, Alderdice, and Sonnier Banks. A total of 120 species and 40,724 individuals were identified from video surveys at the three banks. Planktivorous fishes constituted over 87% by number for the three banks, ranging from 81.4% at Sonnier Banks to 94.3% at Alderdice Bank, indicating a direct link to pelagic prey communities, particularly in the deep reef zones. High numbers of groupers, snappers, jacks, and other fishery species were observed on all three features. These sites were nominated as Habitat Areas of Particular Concern (HAPC) by the Gulf of Mexico Fishery Council in March 2004. Data obtained during this project will contribute to benthic habitat characterization and assessment of the associated fish communities through future SCUBA, ROV, and submersible missions, and allow comparisons to other deep reef ecosystems found throughout the Gulf of Mexico and western Atlantic Ocean.

The relationships between fish assemblages and the amount of bottom horizontal beam exposed at California oil platforms: fish habitat preferences at man-made platforms and (by inference) at natural reefs

Between 1995 and 2002, we surveyed fish assemblages at seven oil platforms off southern and central California using the manned research submersible Delta. At each platform, there is a large horizontal beam situated at or near the sea floor. In some instances, shells and sediment have buried this beam and in other instances it is partially or completely exposed. We found that fish species responded in various ways to the amount of exposure of the beam. A few species, such as blackeye goby (Rhinogobiops nicholsii), greenstriped rockfish (Sebastes elongatus), and pink seaperch (Zalembius rosaceus) tended to avoid the beam. However, many species that typically associate with natural rocky outcrops, such as bocaccio (S. paucispinis), cowcod (S. levis), copper (S. caurinus), greenblotched (S. rosenblatti), pinkrose (S. simulator) and vermilion (S. miniatus) rockfishes, were found most often where the beam was exposed. In particular, a group of species (e.g., bocaccio, cowcod, blue (Sebastes mystinus), and vermilion rockfishes) called here the “sheltering habitat” guild, lived primarily where the beam was exposed and formed a crevice. This work demonstrates that the presence of sheltering sites is important in determining the species composition of man-made reefs and, likely, natural reefs. This research also indicates that adding structures that form sheltering sites in and around decommissioned platforms will likely lead to higher densities of many species typical of hard and complex structure.

Potential use of offshore marine structures in rebuilding an overfished rockfish species, bocaccio (Sebastes paucispinis)

Although bocaccio (Sebastes paucispinis) was an economically important rockfish species along the west coast of North America, overfishing has reduced the stock to about 7.4% of its former unfished population. In 2003, using a manned research submersible, we conducted fish surveys around eight oil and gas platforms off southern California as part of an assessment of the potential value of these structures as fish habitat. From these surveys, we estimated that there was a minimum of 430,000 juvenile bocaccio at these eight structures. We determined this number to be about 20% of the average number of juvenile bocaccio that survive annually for the geographic range of the species. When these juveniles become adults, they will contribute about one percent (0.8%) of the additional amount of fish needed to rebuild the Pacific Coast population. By comparison, juvenile bocaccio recruitment to nearshore natural nursery grounds, as determined through regional scuba surveys, was low in the same year. This research demonstrates that a relatively small amount of artificial nursery habitat may be quite valuable in rebuilding an overfished species.

Trawl-induced Damage to Sponges Observed From a Research Submersible

Three experimental trawl paths subjected to a single pass with the trawl in 1996 in about 200 m of water on the eastern Gulf of Alaska continental shelf were revisited in July 1997, 1 year post-trawl. Many large, erect sponges, the taxa impacted most significantly, had been removed or damaged by the trawl. Sponges in the cold, deep water of the Gulf of Alaska were slow to recover from trawling effects. These findings contrast with recovery times for shallow, warmwater sponges and may have fishery management implications for cold-water regions.

Submersible Observations on Lingcod, Ophiodon elongatus, Nesting Below 30 m off Sitka, Alaska

A research submersible was used to delineate the depth distribution of lingcod, Ophiodon elongatus, nests (egg masses) below 30 m. Although nests were not seen deeper than 97 m, behavior and dark coloration distinctive of nest-guarding lingcod were seen as deep as 126 m. Males guarding nests were distinctly colored, i.e., dark with little or no mottling, and most were obviously scarred. Two types of guarding behaviors were observed: 1) Males lying directly on or beside the nest and remaining nearly motionless unless touched and 2) males lying on a sentry post and defending the nest when other fish swam close.

Micronekton of the North Pacific

1. INTRODUCTION 1.1 Working Group History 2. SPECIES COMPOSITION AND DISTRIBUTION PATTERNS RELATED TO WATER MASSES 2.1 Mesopelagic Fishes 2.1.1 Dominant families 2.1.2 Large-scale feeding and/or spawning migration or expatriation? 2.1.3 Definition of water masses 2.1.4 Species composition 2.2 Crustacean Micronekton 2.2.1 Euphausiids 2.2.2 Mysids and decapods 2.3 Cephalopod Micronekton 2.3.1 Family Enoploteuthidae 2.3.2 Family Gonatidae 2.3.3 Family Onychoteuthidae 2.3.4 Family Pyroteuthidae 2.3.5 Other cephalopods 3. VERTICAL DISTRIBUTION PATTERNS 3.1 Mesopelagic Fishes 3.1.1 Significance of diel vertical migration 3.1.2 DVM patterns 3.1.3 Ontogenetic change in DVM patterns 3.2 Crustacean Micronekton 3.3 Cephalopod Micronekton 4. BIOMASS PATTERNS 4.1 Micronektonic Fish 5. LIFE HISTORY 5.1 Fish Micronekton 5.1.1 Age and growth 5.1.2 Production 5.1.3 Reproduction 5.1.4 Mortality 5.2 Crustacean Micronekton 5.2.1 Age and growth 5.2.2 Production 5.2.3 Reproduction and early life history 5.2.4 Mortality 5.3 Cephalopod Micronekton 5.3.1 Age and growth 5.3.2 Production 5.3.3 Reproduction and early life history 5.3.4 Mortality 6. ECOLOGICAL RELATIONS 6.1 Feeding Habits 6.1.1 Fish micronekton 6.1.2 Crustacean micronekton 6.1.3 Cephalopod micronekton 6.2 Estimating the Impact of Micronekton Predation on Zooplankton 6.2.1 Predation by micronektonic fish 6.3 Predators 6.3.1 Cephalopods 6.3.2 Elasmobranchs 6.3.3 Osteichthyes 6.3.4 Seabirds 6.3.5 Pinnipeds 6.3.6 Cetaceans 6.3.7 Human consumption 6.4 Predation Rate 6.5 Ecosystem Perspectives 6.6 Interactions between Micronekton and Shallow Topographies 7. SAMPLING CONSIDERATIONS 7.1 Net Trawling 7.1.1 Sampling gears 7.1.2 Sampling of surface migratory myctophids 7.1.3 Commercial-sized trawl sampling 7.1.4 Sampling of euphausiids and pelagic decapods 7.2 Acoustic Sampling 7.2.1 Acoustic theory and usage 7.3 Video Observations (Submersible and ROV) 8. SUMMARY OF PRESENT STATE OF KNOWLEDGE 8.1 Fish Micronekton 8.2 Crustacean Micronekton 8.3 Cephalopod Micronekton 9. RECOMMENDATIONS 10. REFERENCES 11. APPENDICES (122 page document)

Deepwater reef fishes and multibeam bathymetry of the Tortugas South Ecological Reserve, Florida Keys National Marine Sanctuary, Florida

The Tortugas South Ecological Reserve, located along the margin of the southwest Florida carbonate platform, is part of the largest no-take marine reserve in the U.S. Established in July 2001, the reserve is approximately 206 km2 in area, and ranges in depths from 30 m at Riley’s Hump to over 600 m at the southern edge of the reserve. Geological and biological information for the Tortugas South Reserve is lacking, and critical for management of the area. Bathymetric surveys were conducted with a Simrad EM 3000 multibeam echosounder at Riley’s Hump and Miller’s Ledge, located in the northern and central part of the reserve. Resulting data were used to produce basemaps to obtain geological ground truth and visual surveys of biological communities, including reef fishes. Visual surveys were conducted using SCUBA and the Phantom S2 Remotely Operated Vehicle (ROV) at Riley’s Hump. Visual surveys were conducted using the ROV and the Deepworker 2000 research submersible along Miller’s Ledge, within and outside of the reserve. A total of 108 fishes were recorded during SCUBA, ROV, and submersible observations. Replicate survey transects resulted in over 50 fishes documented at Miller’s Ledge, and eight of the top ten most abundant species were planktivores. Many species of groupers, including scamp (Mycteroperca phenax), red grouper (Epinephelus morio), snowy grouper (E. niveatus), speckled hind (E. drummondhayi), and Warsaw grouper (E. nigritus), are present in the sanctuary. Numerous aggregations of scamp and a bicolor phase of the Warsaw grouper were observed, indicating the importance of Miller’s Ledge as a potential spawning location for both commercially important and rare deep reef species, and as a potential source of larval recruits for the Florida Keys and other deep reef ecosystems of Florida

Multiscale habitat associations of deepwater demersal fishes off central California

Fish-habitat associations were examined at three spatial scales in Monterey Bay, California, to determine how benthic habitats and landscape configuration have structured deepwater demersal fish assemblages. Fish counts and habitat variables were quantified by using observer and video data collected from a submersible. Fish responded to benthic habitats at scales ranging from cm’s to km’s. At broad-scales (km’s), habitat strata classified from acoustic maps were a strong predictor of fish assemblage composition. At intermediate-scales (m’s−100 m’s), fish species were associated with specific substratum patch types. At fine-scales (<1 m), microhabitat associations revealed differing degrees of microhabitat specificity, and for some species revealed niche separation within patches. The use of habitat characteristics in ecosystembased management, particularly as a surrogate for species distributions, will depend on resolving fish-habitat associations and habitat complexity over multiple scales.

Benthic invertebrates that form habitat on deep banks off southern California, with special reference to deep sea coral

There is increasing interest in the potential impacts that fishing activities have on megafaunal benthic invertebrates occurring in continental shelf and slope ecosystems. We examined how the structure, size, and high-density aggregations of invertebrates provided structural relief for fishes in continental shelf and slope ecosystems off southern California. We made 112 dives in a submersible at 32−320 m water depth, surveying a variety of habitats from high-relief rock to flat sand and mud. Using quantitative video transect methods, we made 12,360 observations of 15 structure-form-ing invertebrate taxa and 521,898 individuals. We estimated size and incidence of epizoic animals on 9105 sponges, black corals, and gorgonians. Size variation among structure-form-ing invertebrates was significant and 90% of the individuals were <0.5 m high. Less than 1% of the observations of organisms actually sheltering in or located on invertebrates involved fishes. From the analysis of spatial associations between fishes and large invertebrates, six of 108 fish species were found more often adjacent to invertebrate colonies than the number of fish predicted by the fish-density data from transects. This finding indicates that there may be spatial associations that do not necessarily include physical contact with the sponges and corals. However, the median distances between these six fish species and the invertebrates were not particularly small (1.0−5.5 m). Thus, it is likely that these fishes and invertebrates are present together in the same habitats but that there is not necessarily a functional relationship between these groups of organisms. Regardless of their associations with fishes, these invertebrates provide structure and diversity for continental shelf ecosystems off southern California and certainly deserve the attention of scientists undertaking future conservation efforts.