A towed camera sled for estimating abundance of juvenile flatfishes and habitat characteristics: Comparison with beam trawls and divers

The 'shallow water refuge hypothesis' (SWRH) holds that predation upon juvenile fish and crustaceans is reduced in shallow water because larger predatory fish increase in abundance with depth. We tested predictions of this hypothesis in 2 Kodiak Island flatfish nurseries, Pillar Creek Cove and Holiday Beach, using baited camera, tethering and video sled techniques. Baited camera deployments during 2007 indicated that predators increased with depth in both nurseries. In the same year, tethering indicated increased mortality of juvenile flatfish with increased depth. In contrast, video sled data from 2003 and 2004 indicated that predator abundance increased with depth at Holiday Beach, but not at Pillar Creek Cove. At Holiday Beach, juvenile abundance decreased rapidly with depth, while at Pillar Creek Cove abundance increased slightly with depth. Thus, predator-predation distribution over 3 yr at Holiday Beach was consistent with the SWRH, while at Pillar Creek Cove it was more variable. Although the SWRH is normally considered in the context of waters < 2 m in depth, our results suggest that it may have efficacy for deeper water, with the relative depth distribution of predators and suitable juvenile habitat being more relevant than absolute depth.

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Testing the shallow water refuge hypothesis in flatfish nurseries

Ryer¹,

Laurel²,

Stoner³

2010

“…SCUBA divers) in collecting fish occurrence data. They are capable of being deployed at depths and times that are dangerous for divers (Assis et al 2007), provide a permanent record of survey (Watson et al 2005), afford accurate positioning when coupled with differential GPS and acoustic positioning, enable high replication and, in the case of drift/towed and ROV, capture transitions between different habitat types (Spencer et al 2005). However, video-based survey methods also have a number of disadvantages, including restricted field of view and the need for high water clarity (Murphy & Jenkins 2010).…”

mentioning

confidence: 99%

Habitat suitability for marine fishes using presence-only modelling and multibeam sonar

Monk¹,

Ierodiaconou²,

Versace³

et al. 2010

Improved access to multibeam sonar and underwater video technology is enabling scientists to use spatially-explicit, predictive modelling to improve our understanding of marine ecosystems. With the growing number of modelling approaches available, knowledge of the relative performance of different models in the marine environment is required. Habitat suitability of 5 demersal fish taxa in Discovery Bay, south-east Australia, were modelled using 10 presence-only algorithms: BIOCLIM, DOMAIN, ENFA (distance geometric mean [GM], distance harmonic mean [HM], median [M], area-adjusted median [Ma], median + extremum [Me], area-adjusted median + extremum [Mae] and minimum distance [Min]), and MAXENT. Model performance was assessed using kappa and area under curve (AUC) of the receiver operator characteristic. The influence of spatial range (area of occupancy) and environmental niches (marginality and tolerance) on modelling performance were also tested. MAXENT generally performed best, followed by ENFA-GM and -HM, DOMAIN, BIO-CLIM, ENFA-M, -Min, -Ma, -Mae and -Me algorithms. Fish with clearly definable niches (i.e. high marginality) were most accurately modelled. Generally, Euclidean distance to nearest reef, HSI-b (backscatter), rugosity and maximum curvature were the most important variables in determining suitable habitat for the 5 demersal fish taxa investigated. This comparative study encourages ongoing use of presence-only approaches, particularly MAXENT, in modelling suitable habitat for demersal marine fishes. KEY WORDS: Species distribution modelling · Multibeam sonar · Towed-video · MAXENT · ENFA · BIOCLIM · DOMAIN Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 420: [157][158][159][160][161][162][163][164][165][166][167][168][169][170][171][172][173][174] 2010 Parallel to the development and application of species distribution modelling in the marine environment, is the increasing access to multibeam sonar (MBES) technology and underwater video systems. These technological developments, coupled with advances in geographic information systems and computational power, make it possible to survey large regions of seafloor with unprecedented accuracy and resolution (Nasby-Lucas et al. 2002, Iampietro et al. 2005, Wilson et al. 2007. MBES datasets are ideal for the application of a variety of terrainanalysis techniques, which form predictor variable datasets for input into models (see Wilson et al. 2007).While traditionally used for assessing sessile species, 'passive' underwater video systems such as drop video, towed/drift video and remotely operated vehicles (ROV) are increasingly being used as cost-effective, non-destructive methods for assessing marine fish species distributions (Morrison & Carbines 2006, Anderson & Yoklavich 2007. These video-based survey methods have significant advantages over traditional methods (e.g. SCUBA divers) in collecting fish occurrence data. They are capable of being deployed at depths and times that are dangerous for ...

“…Video surveys of age-0 flatfish and worm tubes were conducted using a towed camera sled (Spencer et al 2005). Briefly, the sled was towed by a 9 m vessel at an average speed of 60 cm s −1 along the bottom.…”

Section: Towed Camera Assessmentmentioning

confidence: 99%

“…However, the video records after January were excluded from the analysis due to poor visibility. Each survey was completed in 2.5 to 3.0 h, and data (recorded video, GPS; Table 2) were sent back to the Hatfield Marine Science Center (Newport, OR) for video analysis and post-processing (see Spencer et al 2005). …”

mentioning

confidence: 99%

Effects of natural and anthropogenic disturbance on polychaete worm tubes and age-0 flatfish distribution

Laurel

Ryer²,

Spencer³

et al. 2012

Tubes of the ampharetid polychaete Sabellides sibirica are a prominent yet spatially variable habitat feature in shallow-water flatfish nurseries around Kodiak, Alaska, USA. Juvenile flatfish associate with the edges of worm tube regions but seldom use the dense 'turf-like' worm beds that sometimes form on the bottom in the late summer. The present study used a fine-scale analysis (2 to 3 m) to examine how juvenile flatfish distribution changed with worm tube heterogeneity, i.e. density and patchiness. Using a video sled, 8 transect lines (~250 m each) were repeatedly surveyed from late summer to mid-winter in a worm tube region of Pillar Creek Cove, half of which were experimentally disturbed using simulated trawl gear. Results indicated that juvenile flatfish (mainly northern rock sole Lepidopsetta polyxystra) increasingly use patches of bare substrate as worm tube densities increase. However, the simulated trawl disturbance resulted in a unique kind of patchiness, typified by long, thin exposed regions of bare substrate referred to as 'combing'. Unlike natural patches, evidence of combing disappeared 2.5 mo after the initial disturbance, whereas natural patches persisted throughout the entire study. Flatfish abundance increased in trawl-disturbed worm tube beds for only a short period (2 d), possibly due to episodic foraging opportunities rather than physical changes in habitat. These results indicate that worm tube habitat is provisionally resilient to disturbance, and its heterogeneity (density, patchiness, and patch type) is an important component of habitat quality for juvenile flatfish in Alaska. KEY WORDS: Coastal habitats · Benthic recovery · Patchiness · Habitat heterogeneity · Northern rock soleResale or republication not permitted without written consent of the publisher Mar Ecol Prog Ser 466: 193-203, 2012 habitat features in shaping juvenile flatfish distributions of Pacific halibut Hippoglossus stenolepsis and northern rock sole Lepidopsetta polyxystra (Stoner & Titgen 2003, Ryer et al. 2004 as well as plaice Pleuronectes platessa (Pihl et al. 2005, Rabaut et al. 2007). However, in subtidal regions, the importance of emergent habitat on processes in fish nursery areas is poorly understood, likely because the cost and logistic challenges necessitate the use of remotely operated vehicles (ROVs) and submersibles to assess such habitat features (Malatesta & Auster 1999, Diaz et al. 2003, Ryer et al. 2010. Therefore, much of our understanding of habitat processes for flatfish is based on coarser scales (e.g. trawl surveys) and abiotic factors such as temperature, salinity, depth, and bottom hardness.Alaska currently supports some of the largest commercial flatfish fisheries, and many of the target species are highly abundant in subtidal coastal areas (10 to 30 m) during summer and fall (Norcross & Mueter 1999). In Kodiak, Alaska, USA, several of these nursery areas have been the focus of process-based studies of habitat function on growth and survival in age-0 juvenile rock sole and halib...