Underwater video for observing the ecosystem: results and future developments

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Underwater video for observing the ecosystem
results and future developments

• Verena Trenkel, IFREMER, France

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Questions fisheries scientists are being asked

• Traditionally
• How many (commercial) fish are there ?
• How many can be fished ?
• New awareness
• What impact does fishing have on the environment,
  on non-target species, on biodiversity, ?
• How can we manage multispecies fisheries taking
  account of the environment ?

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Fisheries management from an ecosystem perspective

• Context Demersal species
• Challenge for fisheries scientists
• single species ? multispecies ? ecosystem
  management
• Current data collection methods
• scientific trawling
• catchability depends on species and is unknown
• spatial integration of information
• commercial fishing
• location/timing non-random

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Additional data collection requirements

• Ecological information
• form of spatial species distributions
• habitat preferences (substrate, physical
  conditions,)
• species co-occurrence
• Population information
•  absolute abundance/density
• Impact of fishing
• habitat change/destruction (trawl traces)

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Exploratory study

• Technical details
• Summer 2001 in Norwegian sea at around 2000 m
• ROV Victor 6000 (IFREMER)
• Objectives
• Abundance estimation of glacial eelpout
• Transects
• Attraction to bait
• Spatial distribution
• Study of reaction to ROV

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Case study Glacial eelpout
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Survey design Transects
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Numbers per time interval (10 mins)
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Results for glacial eelpout

• Spatial distribution
• variance mean
• Poisson distribution
• Population density
• 1.1 individuals per 10 minutes
• in one meter wide strip
• Behaviour
• slow swimming
• immobilisation on approach of ROV
• or short escape

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What remains to be done to validate observations

• Estimate fish reaction to
• light
• noise
• water displacement
• Compare visual observations to traditional
  methods
• Combine visual observations with fisheries
  information

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Future plans

• ViTal research cruise on continental slope of
  Bay of Biscay
• 700 1200 m
• 3 locations
• Objectives
• study fish reaction to ROV (light, noise)
• abundance/density estimates
• comparison with fixed camera
• comparison with trawl data
• collection of ecological information on deep-sea
  species (fish and benthos)

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Future plans

• Models
• Development of models for estimating population
  densities in wider area (use of environmental
  covariates)
• Development of population dynamics models using
  small scale (video) and large scale (trawl) data
• Image analysis for habitat classification (?)
• Image analysis for facilitating fish counting (?)
• Data collection with ROV/AUV
• acoustic data