1 Underwater video for observing the ecosystem: results and future developments Verena Trenkel, IFREMER, France

2 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 ?

3 Fisheries management from an ecosystem perspective Context : Demersal species Challenge for fisheries scientists single species  multispecies  ecosystem management Current data collection methods è scientific trawling catchability depends on species and is unknown spatial integration of information è commercial fishing location/timing non-random

4 Additional data collection requirements Ecological information è form of spatial species distributions è habitat preferences (substrate, physical conditions,…) è species co-occurrence Population information è ’absolute’ abundance/density Impact of fishing è habitat change/destruction (trawl traces)

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

6

7

8 Case study: Glacial eelpout

9 Survey design : Transects

10

11 Numbers per time interval (10 mins)

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

13 What remains to be done to validate observations Estimate fish reaction to è light è noise è water displacement … Compare visual observations to traditional methods Combine visual observations with fisheries information

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

15 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