scholarly journals Modelling the effects of more selective trawl nets on the productivity of European hake (Merluccius merluccius) and deep-water rose shrimp (Parapenaeus longirostris) stocks in the Strait of Sicily

2018 ◽  
Vol 82 (S1) ◽  
pp. 199 ◽  
Author(s):  
Sergio Vitale ◽  
Marco Enea ◽  
Giacomo Milisenda ◽  
Vita Gancitano ◽  
Michele Luca Geraci ◽  
...  
Keyword(s):  
Deep Water ◽  
Ad Hoc ◽  
Size Composition ◽  
Single Species ◽  
Trawl Survey ◽  
Merluccius Merluccius ◽  
Strait Of Sicily ◽  
Stock Recruitment ◽  
By Catch ◽  
European Hake

Single-species Gadget models were used to assess the effects of using a sorting grid mounted on the traditional trawl net used by Sicilian trawlers to exploit the deep-water rose shrimp in the Strait of Sicily. The main commercial by-catch species of this fleet is the European hake (Merluccius merluccius), often caught at sizes well below the minimum conservation reference size. Selectivity curves based on the results of an experimental survey carried out in the area using a commercial trawler equipped with an ad hoc-designed sorting grid were incorporated into single-species Gadget models to forecast the effects of changing fishery selectivity on the performance of the two stocks in terms of catch and biomass. The models included catch data from the Italian, Tunisian and Maltese fleets as well as MEDITS trawl survey data for the period 2002-2016. Several scenarios were defined to simulate the effect of the Italian trawlers’ adopting the sorting grid under different stock-recruitment assumptions. The results obtained, when compared with status quo simulations of fishing without a sorting grid mounted on the trawl net, indicated a beneficial effect for both stocks in terms of an increase in biomass and for the fleets in terms of the amount and size composition of annual landings.

Spatial and temporal dynamics of European hake (Merluccius merluccius) in the North Sea

2018 ◽  
Vol 75 (6) ◽  
pp. 2033-2044 ◽  
Author(s):  
Arved Staby ◽  
Jon Egil Skjæraasen ◽  
Audrey J Geffen ◽  
Daniel Howell
Keyword(s):  
North Sea ◽  
Temporal Dynamics ◽  
Trawl Survey ◽  
Merluccius Merluccius ◽  
Frequency Distributions ◽  
The North ◽  
The North Sea ◽  
Northern North Sea ◽  
Central North Sea ◽  
European Hake

Abstract Catches of European hake (Merluccius merluccius) in the North Sea have increased substantially during the last decade, even though there is no directed commercial fishery of hake in this area. We analysed the spatial distributions of hake in the northern the parts of its range, (where it is less well-studied), using ICES international bottom trawl survey data from 1997 to 2015. We examine length-frequency distributions for (i) distinct modes enabling the assignment of fish into categories which likely corresponded to the ages 1, 2, and 3+ and (ii) patterns of seasonal spatial distribution for the different groups. Age categories 1 and 2 fish were most abundant in the northern North Sea, and appear to remain in the North Sea until 2 years of age, when they move into deeper waters. Their distribution has expanded into the western-central North Sea in the last decade. Age category 3+ fish were most abundant in the northern and central North Sea during summer, indicating a seasonal influx of large individuals into this area likely associated with spawning activity. The distribution of these older fish has gradually expanded westward in both seasons.

scholarly journals Can a square-mesh panel inserted in front of the cod end improve size and species selectivity in Mediterranean trawl fisheries?

2018 ◽  
Vol 75 (5) ◽  
pp. 704-713 ◽  
Author(s):  
Jure Brčić ◽  
Bent Herrmann ◽  
Antonello Sala
Keyword(s):  
Deep Water ◽  
Bottom Trawl ◽  
Horse Mackerel ◽  
Trachurus Trachurus ◽  
Merluccius Merluccius ◽  
Low Probability ◽  
Low Efficiency ◽  
Trawl Fisheries ◽  
European Hake ◽  
Atlantic Horse Mackerel

An experiment was conducted to assess the selectivity in a typical Mediterranean bottom trawl, equipped with a square-mesh panel inserted in front of the cod end, for Atlantic horse mackerel (Trachurus trachurus), European hake (Merluccius merluccius), red mullet (Mullus barbatus), poor cod (Trisopterus minutus), broadtail shortfin squid (Illex coindetii), and deep-water rose shrimp (Parapaeneus longirostris). The release efficiency of undersized individuals through the panel was low. The differences in selectivity between the gear with and without the panel were very small. The low release efficiency of the square-mesh panel was caused by the lack of fish contact with the panel as they drifted towards the cod end, since the average contact probability was estimated not to exceed 9% for any of the species investigated. A low probability of contact with the selection device was thus found to be the reason for the low efficiency of the square-mesh panel.

scholarly journals Bathymetric preferences of juvenile European hake (Merluccius merluccius)

2008 ◽  
Vol 65 (6) ◽  
pp. 963-969 ◽  
Author(s):  
Valerio Bartolino ◽  
Alessandro Ottavi ◽  
Francesco Colloca ◽  
Gian Domenico Ardizzone ◽  
Gunnar Stefánsson
Keyword(s):  
Full Description ◽  
Trawl Survey ◽  
Bathymetric Distribution ◽  
Merluccius Merluccius ◽  
Fisheries Science ◽  
Stable Pattern ◽  
Length Range ◽  
Depth Preference ◽  
Minimum Depth ◽  
European Hake

Abstract Bartolino, V., Ottavi, A., Colloca, F., Ardizzone, G. D., and Stefánsson, G. 2008. Bathymetric preferences of juvenile European hake (Merluccius merluccius). – ICES Journal of Marine Science, 65: 963–969. The concept of a recruit is a basic notion in fisheries science, but it is still far from being an unequivocal term, and many diverse, even ambiguous, definitions can be found in the literature. We propose a more objective and biologically meaningful way to define the length range of recruits for species that have clear bathymetric segregation during the early stages of their life cycle. The bathymetric distribution of juvenile European hake was studied by fitting a thin plate spline to data from the national autumn trawl survey. Hake showed a stable pattern of depth preference in the 6-year dataset examined. Small hake had the greatest preference for depths of 170–220 m and appeared to move slightly deeper when they reached 10-cm total length. Larger hake persisted on the continental shelf with a preference for water 70–100 m deep, especially when they reached 18–20 cm long. The length at migration was defined as the length at which the minimum depth preference was shown, and it ranged between 13.2 and 15.8 cm depending on the year. There was a relationship between length at and depth of migration, and we provide a full description of the depth preference of juvenile hake, and test the effectiveness of the analytical approach used.

scholarly journals How Fishery Collapses: The Case of Lepidopus caudatus (Pisces: Trichiuridae) in the Strait of Sicily (Central Mediterranean)

2021 ◽  
Vol 7 ◽  
Author(s):  
Fabio Falsone ◽  
Danilo Scannella ◽  
Michele Luca Geraci ◽  
Vita Gancitano ◽  
Sergio Vitale ◽  
...  
Keyword(s):  
Ad Hoc ◽  
Maximum Sustainable Yield ◽  
Sustainable Yield ◽  
Trawl Survey ◽  
Progressive Reduction ◽  
Central Mediterranean ◽  
Yield Model ◽  
Strait Of Sicily ◽  
Management Measures ◽  
Using Data

The silver scabbardfish Lepidopus caudatus is a mesopelagic species living on the shelf and slope down to 600 m in temperate seas all around the world. In the Mediterranean, the species is caught mainly by longlines with a marked seasonality. In the early 90s in the Strait of Sicily (Central Mediterranean Sea), a new fishery targeting L. caudatus was developed. This fishery uses an ad hoc pelagic trawl gear called “spatolara.” Vessels using spatolara have increased from 1 in 1993 to 10 in 2007 with a growth of catches of up to 1,200 tons in 2011. Development of this fishery was not regulated by any specific management measures and, due to the progressive reduction of catch to 169 tons, only one vessel was active in 2018. The availability of catch and biomass indices from trawl survey since the beginning of trawling exploitation allowed providing the first assessment of the state of L. caudatus stock in the Central Mediterranean (GFCM Geographical Sub-Area 16) by using data-limited methods. Catch-Maximum Sustainable Yield (CMSY) and Bayesian State Space Schaefer model (BSM) were fitted to landings and abundance indices (2004–2018). The Abundance-Maximum Sustainable Yield model (AMSY) was also applied to survey data from 1994 (1 year after the start of the spatolara fishery) to 2018 to further corroborate the results. BSM prediction of biomass levels was just above 50% of BMSY, whereas AMSY estimated the current stock levels below 50% of BMSY. The BSM was used for forecasting B/BMSY and catches under different fishing scenarios. Although current exploitation was very close to FMSY, more than a decade would be needed to rebuild the stock to biomass levels producing MSY. A faster rebuilding could be achieved by fishing at least 80% of FMSY, with minimal loss in yield over the next 5–8 years. Following the development of a new fishery since the beginning, the study provides a further example of how unregulated exploitation leads to a heavy overfished state of stock and collapse of fishing activities.

scholarly journals Reproductive features of the deep-water rose shrimp, Parapenaeus longirostris (Crustacea: Penaeidae), in the Strait of Sicily

2010 ◽  
Vol 11 (1) ◽  
pp. 81 ◽  
Author(s):  
M.L. BIANCHINI ◽  
L. DI STEFANO ◽  
S. RAGONESE
Keyword(s):  
Deep Water ◽  
Oocyte Diameter ◽  
Trawl Survey ◽  
Frequency Distributions ◽  
Strait Of Sicily ◽  
Life Traits ◽  
Parapenaeus Longirostris ◽  
The Mediterranean ◽  
The Rose ◽  
Trawl Fisheries

The deep‑water rose shrimp, Parapenaeus longirostris (Lucas, 1846), is one of the most valuable and heavily exploited demersal species of the Mediterranean bottom trawl fisheries. The basic life traits of this shrimp, in particular its reproductive aspects, are regularly monitored during experimental trawl surveys carried out in the Mediterranean Sea. Gonadic condition and maturity status for estimating the size at onset of sexual maturity are commonly assessed in females, using macroscopic color scales, histologically validated only in a few geographical areas. In this study, histological analyses were performed on rose shrimps collected from a trawl survey carried out in the Strait of Sicily, in order to support the empirical 4‑stage macroscopic scale locally employed. Ovaries from females of different sizes, ranging between 16 mm and 40 mm carapace length, were collected and used for microscopic examination of their structure, for oocytes counts and for oocyte diameter frequency distributions; oocytes diameter was measured by imaging analysis. The collected data were also used to estimate other basic vital parameters of the rose shrimp population. The histological observations show a broad correspondence between ovarian development and macroscopic features; therefore, the classifications derived by the empirical scale remain suitable for estimating the maturity parameters.

Mesoscale variability in the trophic ecology of the European hake Merluccius merluccius in the Strait of Sicily

Hydrobiologia ◽  
2017 ◽  
Vol 821 (1) ◽  
pp. 57-72 ◽  
Author(s):  
E. Fanelli ◽  
P. Rumolo ◽  
M. Barra ◽  
G. Basilone ◽  
S. Genovese ◽  
...  
Keyword(s):  
Trophic Ecology ◽  
Mesoscale Variability ◽  
Merluccius Merluccius ◽  
Strait Of Sicily ◽  
European Hake

scholarly journals First Record ofAnisakis simplexThird-Stage Larvae (Nematoda, Anisakidae) in European HakeMerluccius merluccius lessepsianusin Egyptian Water

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Yasmin Abou-Rahma ◽  
Rewaida Abdel-Gaber ◽  
Amira Kamal Ahmed
Keyword(s):  
Red Sea ◽  
Positive Relationship ◽  
First Record ◽  
Type I ◽  
Merluccius Merluccius ◽  
Molecular Analyses ◽  
Fish Samples ◽  
Third Stage ◽  
European Hake ◽  
Anisakid Larvae

The prevalence of infection and the identification of anisakid larvae in European hakeMerluccius merluccius lessepsianusfrom Hurghada City, Red Sea Governorate, Egypt, were investigated. Fish samples were collected during the period of February and November 2014. Twenty-two (36.66%) out of sixty examined fish specimens were found to be naturally infected withAnisakistype I larvae mostly found as encapsulated larvae in visceral organs. There was a positive relationship between host length/weight and prevalence of infection. Based on morphological, morphometric, and molecular analyses, these nematodes were identified as third-stage larvae ofAnisakis simplex. The present study was considered as the first report of anisakid larvae from European hake in the Egyptian water.

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