188
1
Introduction
The Common Fisheries Policy has been
reformed in January 2014, resulting in new
management measures. These new measures
aim at overcoming the shortcomings of the previous management regime especially regarding
the issues related to MSY (maximum sustainable yield), mixed fisheries, spatial dynamics,
discarding behavior, and data-limited species.
Creative tools are central to the management
strategy evaluation (MSE) process. These
include new spatially explicit harvest control
rules and bio-economic models, which can
account for fish population dynamics and fishing reaction to a variety of management scenarios. In this study, innovative harvest control
rules (HCR) have been proposed to adapt catch
quotas (TAC) to the value taken by a range of
indicators traditionally used in EU fisheries
management plans but also alternative status/
pressure indicators that do not require analytical
stock assessments (Butterworth et al. 2010;
Apostolaki and Hillary 2009).
In the Eastern English Channel (EEC) (ICES
Division VIId), a diversity of fleets targets a large
variety of species with various gears. The spatial
and temporal dynamics of these fleets depend
both on fish population dynamics and constraints
applied on fishermen (management, economics,
etc.). The development of new HCRs is complicated by the mixed nature of the fisheries with
risks of increasing discards and effort transfers
from one species to another. To allow the evaluation of new HCRs on fish communities and fleets
accounting for these risks, we developed a spatially explicit model, using the ISIS-Fish software. The framework embodies a spatialized
operational model which simulates the dynamics
of the mixed fisheries in the Eastern Channel
including the spatial dynamics of the main species targeted (sole, plaice, scallops, red mullet,
etc.) and the dynamics of the fleets driven by a
fishing behavior model. We present the spatiotemporal analyses of the fishery dynamics that
resulted in the modeling choices and parameterization of ISIS-Fish.
2
Analysis of the Fishery
In order to assess the impact of new management
measures on the EEC fisheries, the spatio-temporal
structure and dynamics of both fleets and fish
populations have to be understood and described.
2.1
Structure of the Fleets
and the Fishing Activity
We based our analysis of fishing activity on the
segmentation created by the French Fishery
Information System (SIH), which groups French
vessels based on the main, or two main, gears
used during the year (hereafter denominated IFRfleet). The two most valuable species landed by
French fleets in the EEC are common sole (Solea
solea) and scallops (Pecten maximus). The majority of sole landings comes from netters and, to a
more limited extent, from bottom or mixed trawlers. Scallops are mainly landed by dredgers. We
focused on these four IFR-fleets, consisting of a
total of 448 boats in average over 2008–2010,
and pooled the others into an inexplicit fleet
“OTHER.” The rest of the value landed by these
four fleets is mainly made on cephalopods, sea
bass, whiting, red mullet, cod, and plaice (Fig. 1).
The cartography of fishing effort by fleet
segment revealed that effort allocation depends
largely on home region (north of France and
Normandy) and vessel length class (<10 m,
10–12 m, 12–18 m, 18–24 m, 24–40 m, and
>40 m). IFR-fleets were consequently further
segmented according to length class and harbor (Fig. 2).
Some fleet segments contain less than three
vessels which prevent access to economic data at
the fleet scale. Possible grouping of fleet segments of approximate same size and displaying
the same activity were investigated through a
hierarchical ascendant classification on fishing
time per métier (gear x statistical rectangle)
within each fleet (IFR-fleets and harbor). The
small segments that could not be grouped with
others were not explicitly described and pooled
with the “OTHER” fleet bringing the number of
S. Lehuta et al.
1
Introduction
The Common Fisheries Policy has been
reformed in January 2014, resulting in new
management measures. These new measures
aim at overcoming the shortcomings of the previous management regime especially regarding
the issues related to MSY (maximum sustainable yield), mixed fisheries, spatial dynamics,
discarding behavior, and data-limited species.
Creative tools are central to the management
strategy evaluation (MSE) process. These
include new spatially explicit harvest control
rules and bio-economic models, which can
account for fish population dynamics and fishing reaction to a variety of management scenarios. In this study, innovative harvest control
rules (HCR) have been proposed to adapt catch
quotas (TAC) to the value taken by a range of
indicators traditionally used in EU fisheries
management plans but also alternative status/
pressure indicators that do not require analytical
stock assessments (Butterworth et al. 2010;
Apostolaki and Hillary 2009).
In the Eastern English Channel (EEC) (ICES
Division VIId), a diversity of fleets targets a large
variety of species with various gears. The spatial
and temporal dynamics of these fleets depend
both on fish population dynamics and constraints
applied on fishermen (management, economics,
etc.). The development of new HCRs is complicated by the mixed nature of the fisheries with
risks of increasing discards and effort transfers
from one species to another. To allow the evaluation of new HCRs on fish communities and fleets
accounting for these risks, we developed a spatially explicit model, using the ISIS-Fish software. The framework embodies a spatialized
operational model which simulates the dynamics
of the mixed fisheries in the Eastern Channel
including the spatial dynamics of the main species targeted (sole, plaice, scallops, red mullet,
etc.) and the dynamics of the fleets driven by a
fishing behavior model. We present the spatiotemporal analyses of the fishery dynamics that
resulted in the modeling choices and parameterization of ISIS-Fish.
2
Analysis of the Fishery
In order to assess the impact of new management
measures on the EEC fisheries, the spatio-temporal
structure and dynamics of both fleets and fish
populations have to be understood and described.
2.1
Structure of the Fleets
and the Fishing Activity
We based our analysis of fishing activity on the
segmentation created by the French Fishery
Information System (SIH), which groups French
vessels based on the main, or two main, gears
used during the year (hereafter denominated IFRfleet). The two most valuable species landed by
French fleets in the EEC are common sole (Solea
solea) and scallops (Pecten maximus). The majority of sole landings comes from netters and, to a
more limited extent, from bottom or mixed trawlers. Scallops are mainly landed by dredgers. We
focused on these four IFR-fleets, consisting of a
total of 448 boats in average over 2008–2010,
and pooled the others into an inexplicit fleet
“OTHER.” The rest of the value landed by these
four fleets is mainly made on cephalopods, sea
bass, whiting, red mullet, cod, and plaice (Fig. 1).
The cartography of fishing effort by fleet
segment revealed that effort allocation depends
largely on home region (north of France and
Normandy) and vessel length class (<10 m,
10–12 m, 12–18 m, 18–24 m, 24–40 m, and
>40 m). IFR-fleets were consequently further
segmented according to length class and harbor (Fig. 2).
Some fleet segments contain less than three
vessels which prevent access to economic data at
the fleet scale. Possible grouping of fleet segments of approximate same size and displaying
the same activity were investigated through a
hierarchical ascendant classification on fishing
time per métier (gear x statistical rectangle)
within each fleet (IFR-fleets and harbor). The
small segments that could not be grouped with
others were not explicitly described and pooled
with the “OTHER” fleet bringing the number of
S. Lehuta et al.