Biological State and Trend
Habitat and Biology
Climatic zone: Tropical. Bottom type: Hard rocky bottom. Depth zone: Shelf (50 m - 200 m). Horizontal distribution: Neritic. Vertical distribution: Demersal.
Geographical Distribution
Jurisdictional distribution: National
Resource Structure
Considered a single stock: No
In Cape Verde waters, the Esmoregal (
Seriola spp.) family consists of three species, and is thus considered as a shared stock.
Exploitation
CATCH: The catch for this species shows irregular fluctuations with a decreasing trend. The average annual catch of these two species over the period is 79 tonnes (Table 2.13.3a and Figure 2.13.3a).
FISHING EFFORT: The data on artisanal fishing effort (number of trips) show very few variations over the period 1996-2015. The average annual effort for the period is 139 695 trips. It is important to emphasize that the artisanal fishing effort covers all the species (Table 2.13.3b).
CPUE: The CPUE for the species
Seriola spp. is stable between 1996 and 2004, and shows an increasing trend from 2004 to 2009. The last years show a decreasing trend (Table 2.13.3c and Figure 2.13.3b).
Fishery Indicators
| Type | Measure | Value | Unit | Time period |
|---|
| Production | Catch | 76 | tonnes | 1996 |
| Catch | 69 | tonnes | 1997 |
| Catch | 51 | tonnes | 1998 |
| Catch | 71 | tonnes | 1999 |
| Catch | 81 | tonnes | 2000 |
| Catch | 61 | tonnes | 2001 |
| Catch | 57 | tonnes | 2002 |
| Catch | 56 | tonnes | 2003 |
| Catch | 54 | tonnes | 2004 |
| Catch | 61 | tonnes | 2005 |
| Catch | 64 | tonnes | 2006 |
| Catch | 87 | tonnes | 2007 |
| Catch | 92 | tonnes | 2008 |
| Catch | 119 | tonnes | 2009 |
| Catch | 105 | tonnes | 2010 |
| Catch | 87 | tonnes | 2011 |
| Catch | 112 | tonnes | 2012 |
| Catch | 98 | tonnes | 2013 |
| Catch | 79 | tonnes | 2014 |
| Catch | 92 | tonnes | 2015 |
Assessment
Assessment year: 2017
The CECAF Working Groups have adopted the following Biological Reference Points (BRPs):
- Limit Reference points: BMSY and FMSY
- Target Reference Points: B0.1 and F0.1
Stock status is assigned based on current estimates of fishing mortality (Fcur) and biomass (Bcur) relative to these target and limit reference points (Bcur/BMSY, Fcur/FMSY, Bcur/B0.1, Fcur/F0.1). The results from the stock assessment of this stock are found under the “Biological state and trend section”.
Data
The Working Group used the total artisanal catch series for Esmoregal (
Seriola spp) for the period 1996 to 2015. The abundance indices used were the CPUE of the artisanal lines (kg/trip). The initial input parameters were: r (intrinsic growth rate) = 1.50/year; K (initial biomass) = 700 tonnes and BI/K = 50 percent (biomass of the stock at the start of the data series, compared with the initial biomass).
Assessment Model
Type: Biomass-aggregated
Schaefer dynamic production model
The Schaefer dynamic production model implemented on an Excel spreadsheet was used to evaluate the state of the stocks and the demersal fisheries in the region. This model is described in detail in FAO, 2012.
Overall Assessment Results
No results from the assessment model, but CPUE shows a general decreasing trend (FAO, 2020).
RESULTS: The data do not fit the model for Esmoregal (
Seriola spp.), and thus no conclusion can be drawn from the results of the model. DISCUSSION: The data of catch and CPUE in the last years do not have sufficient contrast to able to apply any assessment model. The catches and CPUE follow the same trend. Furthermore, the data shows two very different patterns before and after 2006 which could indicate a change either in fishing strategy or data collection and reporting. The data series and in particular, the new data provided need to be analyzed and improved before the next meeting.
Scientific Advice
As a precautionary measure the Working Group recommends that the fishing effort should not exceed the current level and that total catch should not exceed the average of the 3 last years (90 tonnes) (FAO, 2020).
Source of information
FAO. 2019. Report of the FAO/CECAF Working Group on the Assessment of Demersal Resources – Subgroup South. Libreville, Gabon, 6–15 September 2017/Rapport du Groupe de travail sur l’évaluation des ressources démersales – Sous-groupe Sud. Libreville, Gabon, 6–15 septembre 2017. CECAF/ECAF series/ FAO/COPACE COPACE/PACE séries no.18/79. Rome.
http://www.fao.org/3/ca2739b/ca2739b.pdfFAO. 2019. Fishery Committee for the Eastern Central Atlantic, Report of the eighth session of the Scientific Sub-Committee, Abidjan, Côte d’Ivoire, 23–26 October 2018 / Comité des pêches pour l’Atlantique Centre-Est Rapport de la huitième session du Sous-Comité scientifique, Abidjan, Côte d’Ivoire, 23–26 octobre 2018. FAO Fisheries and Aquaculture Report / FAO Rapport sur les pêches et l’aquaculture No. 1265. Rome.
http://www.fao.org/3/ca5623b/ca5623b.pdfFAO. 2020. Report of the Twenty-Second Session of the Fishery Committee for the Eastern Central Atlantic, Libreville, Gabon, 17–19 September 2019. Rapport de la vingt-deuxième session du comité des pêches pour l’Atlantique centre-est, Libreville, Gabon, 17–19 septembre 2019. FAO Fisheries and Aquaculture Report / FAO, Rapport sur les pêches et l’aquaculture No. 1303. Rome.
http://www.fao.org/3/ca8000b/CA8000B.pdfBibliography
All references to figures, tables and bibliography in the text are found within the source of information.
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