Mariano Gutiérrez

Acoustic data from fishing vessels: What can be obtained that research vessels cannot offer?

Use of fishing vessels and platforms of opportunity to collect acoustic‐based population distribution and abundance data has been considered since the 1990s. The idea was that low data quality was compensated by large sampling throughout the year, and in areas where research vessels did not sample. We present results and hypotheses on the use of such data from the anchovy and jack mackerel fishing industry in Peru, where many fishing vessels are equipped with SIMRAD ES60 echosounders. First, fishing vessels are selected according to a criteria set. Once “optimal” fishing vessels are selected, we show that exploiting acoustic data from these ships may provide new information. The first is a correlation of fishing activity with fish biomass. Ee analyzed echograms preceding trawl sets. Data on fish biomass and spatial distribution were correlated with catch and catch structure. Additionally, environmental information in an area of 1 nm2 centered on the trawl location was added to the acoustic and fishing dat...

SCHOOL TYPOLOGY AND 3D DYNAMICS: STUDY OF THE BEHAVIOURAL MECHANISMS ALLOWING ADAPTATIONS OF COLLECTIVE STRUCTURE TO ENVIRONMENTAL CHANGES

Being the collective interface with the environment and the exploitation, schools and their typology represent an important life history trait of gregarious fish. Changes in the characteristics of the environment sensu largo induce changes in the school typology, which can be used as indicator of stock adaptive patterns. In order to understand the interactions between school structure and environment patterns, a first step consists in studying the school internal structure and the functioning of fish aggregation inside it and in its surroundings. The paper describes the spatial morphology and dynamics changes in Peruvian Anchovy (Engraulis ringens) schools in Peru using multibeam sonar observation on a station. Different cases of school types are extracted from a data base of around 200 recordings: from small circular well individualized schools to large aggregation surrounded by scattered targets. The internal structure of the aggregations is described at a 10 cm definition scale. The shape and dynamics of internal structures (nuclei) are described. The school edges are measured in shape and dynamics, and the relationship between the school and the fish surrounding the school are measured, using geostatistics and fractal dimensions approaches