Quick link to: EFIMAS home, WP4, CS8

Efimas (sub) case study Ligurian Sea Hake Fishery . CS8

Introduction – Overview description of the (sub)case study

The main objective of this (sub) case study in the frames of the EFIMAS project is to evaluate capacity and/or effort reduction using FLR packages. Technical measures as thought impact on selectivity and therefore fishing mortality are also herein considered. Particularly, this (sub) case study 8 is to investigate Ligurian Sea hake fisheries. The selection of such case-study is based on the desire to carry out, at Mediterranean level, a comparative analysis on fishing areas that, for geographical and stock reasons have common features. On this basis, the Ligurian hake fisheries stand beside the Spanish and Greek (sub)case-studies, in the Golf of Lyon and Aegean Sea, respectively.

Description of the fishery, stocks and management system of the (sub)case study

The hake fishery

Hake (Merluccius merluccius) is one of the most traditional fisheries in the area. Environment and fishing human activities interacts conditioning physical capital use in the sector and, therefore, techniques (gears). A regulation forming the focus of the set restrictions to the fishing area that’s combined with the physical assets and market prices determines the fishermen behaviour in terms of discards, illegal fishing and compliance. It is of importance to describe the morphological characteristics of the fishing area and the interactions between fisheries and the environment for a better comprehension of the fishery driving forces considered into up-building the current model applied to the Ligurian Sea hake fisheries.

Morphological characteristics of the fishing area

Fishery in the Ligurian Sea is usually identified with the fishing activities conducted within Genoa bay. Boundaries of Genoa bay would fall between the waters delimitated by the 44.30’ meridian from the Equator, 08.10’-10.00’ longitude east from Greenwich and the geographical area bordering the Ligurian coast (from Capo Mele to Palmaria Island). The fishing activity, instead, is mainly performed between the western and the eastern Ligurian Riviera (between Cape Sant’Ampeglio and Palmaria Island, including part of La Spezia’s Terrazzo). The continental shelf (limited to a depth of 200 m.) is rather narrow since the seabed slopes down abruptly in the direction of the abyssal plains, beyond the depth of 2000 m. It is only towards the east that the low seabed becomes wider and embraces the entire Tuscan Archipelagos approaching the western coast of Corsica. The 20 meters isobaths almost skims the coast and reaches the depth of 1000 m within the distance of a mile and half to the southeast of Cape Noli. The 2000 m. bathymetric strip runs at about 10 miles to the south of Cape Berta. The Ligurian coast displays a specific feature: the valleys of the Bisagno and Polcevera torrents run on as two current under water canyons which reach beyond the depth of 1000 m., significantly engraving the continental shelf. Mainly rocky, the bathymetric zone within 30 m. is composed of sandstone, limestone and conglomerates, while the sandy shores are relatively small (narrow strip of sand between 30 to 50 m.). Moving away from the coast, the muddy expanses become more and more impalpable beyond the depth of 50 m. and are interrupted by extensive rocky shallow waters of volcanic or organogenesis origin. Between the depth of 200 and 700 m. a number of rocky outcrops can also be found (see fig.1).

Interactions between fisheries and environment

The seabed of the Ligurian Sea is characterised by a rather uneven morphology especially along its shoreline where rocky habitats and cliffs drop vertically to the sea. Whereas the presence of cliffs facilitates the use of small-scale fishing gears, a series of small valleys create authentic under water canyons which significantly engrave the continental shelf. This geographical peculiarity has a crucial role in local fisheries since it prevents any trawling activities. Moreover, the presence of a rather narrow continental shelf represents a negative aspect in itself since this is by far the most productive area of the sea. In fact, its waters, which are also called neritic waters, are the most easily accessible and richest in terms of marine flora and fauna since it contains the most favourable features of illumination, oxygenation and nutritional salts from the coast. From a depth of 10 m. to 500 m., the sequence of rocks, scattered cliffs, artificial barriers, shallow waters, wreckage, hulls, extended formation of madreporic rocks and heaps of waste reduce by two thirds its trawling surfaces. Nevertheless, trawling is generally undertaken in neritic waters though for the most part, the abrupt fall of the seabed towards profound depths makes it impossible and rather dangerous for traditional vessels to go beyond the depth of 200 m. These difficulties are partly compensated by the prospect of harvesting on proper reefs that surface from considerable depths - e.g., Oneglia’s shoals on the western side and Santa Lucia’s shoals on the eastern side, which are notoriously concentrated by Ligurian trawlers. Scarcity of available fishing areas is compensated by technology where the development of cables enabled operators to reach the meso-bathyal strip (bathymetric of 700-800 m.). To perform any trawling activity the length of the cables must approximately be three times that of the bathymetrical level to be touched with the nets. As a synthesis, effort is concentrated at mostly the bathymetric of 50 m where trawlers, small-scale and multipurpose vessels insist.

Figure 1 – Bathymetry of the Ligurian Sea (the 50 meters isobaths, is marked in grey).

Descriptive of the 2005 hake fisheries in the Ligurian Sea

Trawlers, small-scale and multipurpose vessels operate along the 343 km. of the Ligurian coast. This comes under the jurisdiction of 4 maritime districts (Imperia, Savona, Genoa and La Spezia), with 81 landings sites of which only 18 are fishing harbours. Catches are very varied: more than two hundred different species among which are found cartilaginous fish, osseous fish, crustaceans and molluscs. Within the 200 m isobaths approximately 85 species of fish (53 edible) and 46 species of crustaceans (12 edible) are caught1). Among the edible species, the most important from an economic point of view are: the Hake (Merluccius merluccius), the Red mullet (Mullus barbatus), and the Sparidae, and the Horned octopus (Eledone cirrhosa). Hake fisheries in the area under consideration take only a little part of the total national hake catches. At once, 2005 figures for hake captures consists in a small quota (5%) of the total harvesting in the Ligurian Sea (214 tons. whilst 3965 tons, respectively), and amounts to up 7,5% of its value (2,95 mln € whilst 39,26 mln of the totals). Catches of hake occurs during all the month’s year with a relative pick period on April – July (plus 30% on average within the rest of the year). Hake prices are based gears techniques witch operates according niches by distribution channels and open market mechanisms prices varying from 10 €/kg to 20 €/kg., around. The Ligurian Hake fisheries were composed of: 214 vessels with a capacity of 3297 tons of gross tonnage (gt) and an overall engine capacity of 28854 kilowatts. Total effort reaches 77990 fishing days and has employed 794 member-crew units. Of the totals for the Ligurian Hake fisheries are relevant the total labour cost of 10,27 mln € and the total intermediate costs of 15,85 mln €, both forming total operational costs2) totalising 26,12 mln € during 2005. Operational costs by day were around 335 €. Technical and economic figures for each of the fleet segments considered3) were stable in the medium and long past period. 2005 figures for trawlers, small-scale and multipurpose vessels are reported in tables 1 and 2.

Description of the commons, codes, procedure, settings and outputs of simulations for (sub)case study CS8

Descriptive of commons for all simulations

Descriptive of commons for all simulations: three fishing fleets are considered: trawlers, small scale vessels and multipurpose vessels4). Forecasts considers the period 2005-2024. All cases using libraries of the FLCore with the following sources: (a) Biological operating model is the FRL package FLBiol classes of FLCore age-based assessment, 15 hake ages classes considered; (b) MedCost that is a version of the general FLCost adapted to the Mediterranean fisheries; © MedIndicators that is a version of the CommitIndicators also adapted to the Mediterranean fisheries (basically the structure of the economic accounts of the vessels); (d) MedMPA that considers the actions undertaken by fisheries institutional bodies confined into effort, capacity and technical measures; (e) Flexib that is a version of the general code FLPrice that’s embedded prices and costs flexibilities (scenario #0.Current situation, inclusive). For all simulations MedMPA interacts only with the trawler fishing fleet and impacts occurs after three years. No discards5) and no compliance are considered. For all 100 numbers of simulations were run (see above and Efimas wiki).

Descriptive of common codes for all scenarios

Descriptive of common codes for all scenarios: (a) common libraries, as reported before: code Flexib.R (Flex.prof and Flex.land functions). Flex.prof is used to estimate effort or capacity as a function of profit by flexibility coefficient, and Flex.land is used to estimate price as a function of landings by flexibility coefficient. Code Flexib.R was not fully implemented into simulations; code FLPrice.R (FLPrice class and methods) that is a version of FLPrice adapted to Mediterranean fisheries; code MedFLCost.R (FLCost class and methods) that is a version of FLCost adapted to Mediterranean fisheries; code MedIndicators.R (MedInd class and method MedIndEst) that is a version of CommitIndicators adapted to Mediterranean fisheries; and code MedMPA.R (MedMPA class and methods); (b) specific codes by scenarios: code Scenario 0.R (no management action); code Scenario 1.R (effort reduction by 20% in terms of average days at sea with no change in number of vessels); code Scenario 2.R (effort reduction by 20% in terms of average days at sea with no change in number of vessels plus 50% reduction of selection at age 0); code Scenario 3.R (effort reduction by 20% in terms of average days at sea with no change in number of vessels plus 100% reduction of selection at age 0); code Scenario 4.R (effort reduction by 10% in terms of number of vessels) (efimas wiki link); code Scenario 5.R (effort reduction by 10% in terms of number of vessels plus 100% reduction of selection at age 0).

Descriptive of common procedure for all scenarios

Descriptive of common procedure for all scenarios: (a) initial setting for ages and years; (b) initialize objects; © setting values for FLBiol recruitment imposing natural mortality; (d) setting values for FLFleet by fleet segments imposing prices (€/kg), catches (kg), number of vessels (capacity) and fishing days (effort); (e) biological operating model imposing number of simulations, matrix for spawning stock number ssn and for total revenues, and ratios of total revenues on hake revenues; (f) create storage matrices and arrays imposing stock number and weight by age and year, total catches by fleet and year, total landings (biomass/number) by fleet and year, landings in number by fleet and year, landings in weight by fleet and year, matrices for juveniles and spawners, matrices for stock number and biomass, matrices for partial and total fishing mortality, revenue by year and run; (g) start simulations; (h) storing results imposing landings weight and revenues by year for each run, landing number/weight by year and age for each run, stock number by year and age and catch weight; (i) graphs, plotting forecasted total catch (wt), plotting forecasted net revenues, plotting forecasted net revenues per vessel.

Descriptive of common settings for all scenarios

Descriptive of common settings for all scenarios: (a) biological setting using VIT values in the Gulf of Lyon adapted to the Ligurian Sea; (b) spawning stock number SSN for total revenues; © fleet setting using catches in kg, prices in €/kg, VIT landings in kg, selectivity as a catchability parameter, effort in fishing days and capacity in number of vessels.; (d) case specific management issues addressed on effects on effort, capacity and selectivity; (e) costs estimated as a function of effort and capacity; (f) fishing mortality F vector as multiplication of catchability, selectivity and effort; (g) estimates of economic indicators using as variables fleets, costs, crew shares and years; (h) prices using variables last year prices, landings and flexibilities; (i) revenues from other species than hake as proportion of total revenues (applied when relevant); and (j) outputs values in million € and volumes in tons.

Descriptive of common outputs for all scenarios

Descriptive of common outputs for all scenarios: (a) plots for landings, net profits and net profit per vessel by fleet segments and total fleet, and (b) forecast values 2005-2024 for landings, net profit and net profit per vessel including values variations 2006-2009, and total variations 2005-2024 (EFIMAS TABLES 3-8 LIGURIAN SEA HAKE FISHERIES.XLS).

Description of the scenario evaluations and results for (sub)case study CS8

Scenario #0. Current situation: no management action is foreseen

Forecast current exploitation pattern with constant fishing effort by fleet segments and total. Annual recruitment rates vary randomly around the average of previous years. No reference points for stock. Price flexibility is at minus 0.2 within respect landings. Costs varying according to effort and capacity subdivided by maintenance costs, other fixed costs, fuel costs and, finally other variables costs. Prices and costs variations don’t apply to scenario #0. The scenario #0 equilibrium conditions is stable at levels: 214 tons for landings (of which 89 tons for trawlers, 19 tons for multipurpose vessels and 106 tons for small-scale vessels); 13 millions € for net profits (of which 4 mln € for trawlers, 2 mln € for multipurpose vessels and 7 mln € for small-scale vessels), and 106 thousands € for net profits per vessel (of which 54 thousands € for trawlers, 36 thousands € for multipurpose vessels and 16 thousands € for small-scale vessels)( figures rounded).

Scenario #1. Effort reduction by 20% of days at sea from 2006

Command and control policy for trawlers fleet segment imposing a reduction by 20% of effort, all other fleet segments stables. Price flexibility is at minus 0.2 within respect landings. Costs varying according to effort and capacity subdivided by maintenance costs, other fixed costs, fuel costs, and other variables costs. The scenario #1 suggests low variations for landings (2%), for net profits (8%) and for net profits per vessel (3%). All figures decreases for trawlers while for multipurpose vessels and small-scale vessels grows. Benefits in terms of effort reduction for trawlers are distributed between other gears and between vessels. As expected, losses short term impacts are high. During the first year of adoption of the measure (2006) landings and, therefore, economic accounts of the hake fisheries (namely, of the trawler fleet segment) would have a lower performance where zeroing negative impacts would occurs for next periods. Scenario #1 is highly beneficial to the multipurpose and small-scale fleet segments whereas penalise the trawlers fleet segment.

Scenario #2. Effort reduction by 20% of days at sea and selection reduction of 50% at age zero from 2006

Command and control policy for trawlers fleet segment imposing a reduction by 20% of effort (fishing days) and a improvement into selectivity forcing a 50% reduction at hake first class age zero catches, all other fleet segments stables. Price flexibility is at minus 0.2 within respect landings. Costs varying according to effort and capacity subdivided by maintenance costs, other fixed costs, fuel costs, and other variables costs. Implicit the objective of that management: protecting juveniles into the stock biomass. The scenario #2 suggests low variations with respect scenario #0 (the current situation) and variations quite similar to scenario #1. Dynamics of the impacts are similar to those of previous action. Imposing a 50% reduction at recruitment at age class zero is not a major valued added for the Ligurian Sea hake fishery. Effort reduction and effort reduction associated with low improvement on selectivity produces the same positive and negative effects.

Scenario #3. Effort reduction by 20% of days at sea and selection zero at age zero from 2006

Command and control policy for trawlers fleet segment imposing a reduction by 20% of effort (fishing days) and a improvement into selectivity forcing a 100% reduction at hake first class age zero catches, all other fleet segments stables. Price flexibility is at minus 0.2 within respect landings. Costs varying according to effort and capacity subdivided by maintenance costs, other fixed costs, fuel costs, and other variables costs. The scenario #3 implies a serious conservation policy on biomass protecting all the juveniles inside stock. Selectivity on gears is the focus of that management. The scenario #3 suggests low variations for landings, net profits and net profits per vessel (2%, 8% and3%, respectively), that is the same variations as for scenario #1 and scenario #2, and similar dynamics between fleet segments into the fishery (losses for trawlers and gains for multipurpose and small-scale fleet segments). Notwithstanding, scenario#3 forecasts the better fishery results obtained with simulations. A 20% reduction of trawler’s effort and zero tolerance for catching juveniles at age zero will up-grade landings by 2%, net profits by 8% and net profits per vessel by 4%. The apparent conflicting interests among fleet segments (trawlers vis a vis multipurpose and small-scale fleets) is solved trough a negative variation of landings for trawlers (minus 13%) against an average positive variation of landings for multipurpose and small-scale fleets (plus 12%). At same time, net profits and net profits per vessel for trawlers decrease by minus 6% while for the two other segments increase by 15% average rounded.

Scenario #4. Effort reduction by 10% of capacity (number of vessels) from 2006

Command and control policy for trawlers fleet segment imposing a reduction by 10% of capacity (number of vessels), all other fleet segments stables. Price flexibility is at minus 0.2 within respect landings. Costs varying according to effort and capacity subdivided by maintenance costs, other fixed costs, fuel costs, and other variables costs. The scenario #4 implies a based vessel’s retirement management. Forecasts show a general improvement for the hake fisheries (1% on landings, 5% on net profits and 9% for net profits per vessel). Landings of the trawler fleet segment decrease by 7% while increase by 11% for both multipurpose and small-scale fleets. Net profits remain stable for trawlers and increase by a 7% for both others. Net profits per vessel increases by 11% for trawlers against 7% for multipurpose and small-scale fleet segments (figures average rounded). There is a novelty in scenario #4: net profits per vessel up-grades for all the three fleet segments into the fishery. Notwithstanding, it should be noted that net profits per vessel for multipurpose and small-scale fleets in scenario #4 is half values than on scenario #1 to #3. In other terms, considering only multipurpose and small-scale fleet segments, the positive effects of an effort reduction halves adopting a capacity reduction policy. Considering the simplicity of adoption of such management measure and the results obtained by simulations, its appears as the better solution for a up-grading of the economic performance of the vessels. As a matter of fact, low reduction of capacity generates better economic performance and easer applications of measures, compliance comprised.

Scenario #5. Effort reduction by 10% of capacity (number of vessels) and selection reductions by 100% at age zero from 2006

Command and control policy for trawlers fleet segment imposing a reduction by 10% of capacity (number of vessels) plus an improvement into selectivity forcing a 100% reduction of selection at hake first class zero catches, all other fleet segments stables. Price flexibility is at minus 0.2 within respect landings. Costs varying according to effort and capacity subdivided by maintenance costs, other fixed costs, fuel costs, and other variables costs. As for scenario #3 (effort reduction) scenario #5 implies a serious conservation policy on biomass protecting all the juveniles inside stock. The scenario #5 shows similar results than scenario #4. All figures are positives with the exception of the decrease of landings of the trawler fleet segment. Gains and loses dynamics between fleet segments are identical and also levels of those gains and losses. Littler positive variations occur with respect scenario #4. In scenario #5, landings of the fishery grow 1%, net profits grow 6% and net profits per vessel grow 10%. These are the better results obtained by simulations. Low reduction of capacity associated with a high improvement on selectivity of gears generates better economic performance, compliance excluded. Gains and losses comparison between scenario #4 and scenario #5 suggests the major cost of adoption of the latter, in terms of compliance.

Results comparison and conclusions

From scenario #1 to scenario #5 the Efimas model used for (sub) CS8 forecasts realistic positive variations on the fishery performance. The measures are all applied (only) to the trawler fleet segment. Landings, net profits and net profits per vessel are reduced for the trawlers benefiting the artisanal fisheries (multipurpose and small-scale fleet segments) when adopting effort reduction policy. Net profits and net profits per vessel up-grades for all the three fleet segments when adopting a capacity reduction policy. Following a short term decrease on trawler’s landings, due to effort or capacity reductions, level recover is only partial. Effects on net profits and on net profits per vessels are fleet segment’s differentiates according the two different measures, also due to the balance of the conjoint effects of price flexibilities and costs variations with opposite signs at those of revenues. It appears that scenario #3 (effort reduction by 20% of days at sea and selection zero at age zero from 2006) is the better solution for multipurpose and small-scale fleet segments while scenario #4 (effort reduction by 10% of capacity - number of vessels) is the better solution for trawler fleet segment, taken into account compliance. In synthesis, effort reductions appear to be negative for the trawler fleet segment while capacity reductions have positive effects. For multipurpose and small-scale fleet segments both effort or capacity reductions produce benefits. Applying effort control measures gains levels for the artisanal fleet appears high while applying capacity control measures its appears medium. For the global Ligurian Sea hake fishery better performance and compliance is obtained applying capacity control measures.

Recommendations and management signals

Simulations have allowed comparisons between different management options based on effort and capacity control policy. Technical measures like actions upon selectivity are also considered. Reductions of fishing effort (days at sea) and/or fishing capacity (number of vessel), associated or not with negatives changes on selection at age zero of stock recruitment, envisages an improvement of the stock biomass without changing the equilibrium of the status quo. Market forces (price and costs flexibilities) neutralize incentives for a huge intervention into the fishery. Notwithstanding, it’s suggested a soft level of intervention that would improve fishery performance. Landings and net profit of the fishery remains stable in the medium-long period with and without policy interventions due to a good management in the previous past. There is space for little major improvements adopting effort or capacity reduction actions. Results have shown a major positive impact of capacity reduction vis a vis effort reduction. Capacity reduction will improve profits while effort reduction allows stability of employment. As expected from theory short terms impacts occur during the implementation of the alternative actions with a progressive zeroing of the annual impacts. Economics accounts of the fishery are and will be stable with a stock biomass improved in case of adoption of selection zero at age zero of the stock, that is up-grading selectivity. In other terms, it will be at least sufficient to intervene on dimension of the trawlers nets (i.e., major grids of the nets) to improve performance. Effort reduction by a 20% of the trawlers fishing days or a capacity reduction by a 10% of the number of the trawler vessels would allow the fishery to continue at equilibrium associated to higher net profits by vessel via cost reduction. As that it is suggested to not introduce eventual subsidies into fisheries whereas it requested.

Dissemination

The EFIMAS project has produced various simulation models each one applied to the specific case studies. Same procedure has been applied for the (sub) cases of the Mediterranean Hake fisheries. The model and relatives FLR code created are addressed to three different categories of end-users: scientific and academic people, institutional managers and the producers. For the scientific society the current model could contributes to an up-grading of the meaning of the driving forces in Mediterranean fisheries. Evaluations of the simulations could be an excellent exercise for technical analysis comparison between impacts of management measures. For the institutional managers the model allows a short and long period evaluation of biological and socio-economical impacts of standard management options. Finally, for the producer users the model allows forecasts and a better understanding of its dynamics. To date no formal plan of dissemination of the results obtained is foreseen, with the exception of the WP5 complains.

References

  • Arnason, R., P. Coccorese, S. Olafsson, V. Placenti, G. Rizzo, 1997, Comparison of the Icelandic (UI) and Italian (IREPA) Fisheries Management Models, FAIR-CT95-0561 Project.
  • Placenti, V. and G. Rizzo, 1992, “A Bio-Economic Model for the Optimization of a Multi-Species, Multi-Gear Fishery: The Italian Case”, Marine Resource Economics, vol. 7, pp.275-295.
  • V. Placenti 1998, Innovative Integrated Bioeconomic Models for the Management of Multispecies and Multigears Fisheries. Report to the General Directorate for Fisheries, Contract FAIR CT95/0561, EC, DG XIV.
  • Avv. 2006, BIRD-MOD “SUPPORTO METODOLOGICO PER IL MODELLO BIO ECONOMICO BIRD-MOD”. Final Report Italian Ministry of Agriculture and Fishery, Code 6A3.

Acknowledgements

We wish to thank Paolo Accadia (CEMARE, UK) who have full developed the FLR codes applied to the CS8

Participants

Vincenzo Placenti (IREPA, Italy)

Meeting documents and other case specific work – working documents, proposed models and analysis performed

1) The sandy substrata which plunge as far as the 50 m. isobaths are not very frequent, while the habitats that are loaded with most part of coastal trawling are terrigenous mud and the open sea detrital seabed (approx., the former between 50-100 m. and, the latter between 100-150 m.). Epi-bathyal trawling (between 200 and 450 m.) exploits the higher levels of the slope. Local fishermen commonly define this seabed with the expression “a scampi and potassoli” meaning that most part of landings is composed of these species. Besides Norway lobster (Nephrops norvegicus) and Blue whiting (Micromestius potassou), on the epi-bathyal seabed the following species can be caught: Greater forkbeard (Phycis blennioides), European hakes (Merluccius merluccius) of a good size (hakes, in fact, usually tend to move downward as they grow), Blackbelly rosefish (Helicolenus dactylopterus), Four-spot megrim (Lepidorhombus boscii), European conger (Conger conger), Deepwater rose shrimp (Parapenaeus longirostris), different species of shrimps (Solenocera membranacea, Plesionika heterocarpus, Chlorotocus crassicornis, and so on). Among the Cephalopoda, which are almost always in the phase of reproduction, Broadtail shortfin squid (Illex coindetii, Todaropsis eblanae), Speder octopus (Octopus salutii) and Horned octopus (Eledone cirrhosa) can also be harvested on the epi-bathyal seabed.
2) Total operational costs are the sum of the “total intermediate costs” and the “total labour costs”. In economic terms, the value of landings minus the total operational costs, as calculated and reported in the tables and, therefore, applied to the FLEcon codes, is equal to the “gross cash flow”. Gross cash flow (GCF) is equal to the value of the landings minus all expenses, except for depreciation and interests. GCF shows the amount available for interest payments and repayments of loans, and also for depreciation and interest regarding own capital. In other terms, the total operational costs is the up-sum of fuel costs, other running costs, vessel costs and the crew share, excluding depreciation and interest. That structure of vessel economic accounts is conceived according the mechanisms considered into the fishermen behaviour inside the model used for the simulations.
3) Fleet segments herein considered excludes some other gears that catch hake, like purseiners and longliners. The last ones catch hake occasionally and mainly in the half end annual period.
4) Distinction between small scale vessels and multipurpose vessels are made by types of license rather than technical characteristics, even if small-scale vessels are minus than 12 meters while for multipurpose vessels dimension boundaries are no applied. Multipurpose vessels comprise trawlers net licences while trawlers nets is not allowed for small scale vessels.
5) Discards in the Ligurian Sea hake fisheries doesn’t reach 0,8% of total landings thus allowing it’s not inclusion into the simulations.
 
efimas1/wp4/cs8/appr11/main.txt · Last modified: 2008/11/16 01:47 by admin
 
Except where otherwise noted, content on this wiki is licensed under the following license:CC Attribution-Noncommercial-Share Alike 3.0 Unported
Recent changes RSS feed Donate Powered by PHP Valid XHTML 1.0 Valid CSS Driven by DokuWiki