Atlantic chub mackerel (Scomber colias) growth and reproduction off the Portuguese coast in relation to the population dynamics
Cristina
Nunes1*,
Andreia
V.
Silva1,
Diana
Feijó1,
Eduardo
Soares1,
Ana Carolina
Porfírio2,
Delfina
Morais1,
Georgina
Correia1,
Pedro
Da Conceição1,
Maria Do Carmo
Silva1,
Corina
Chaves1,
Vitor
J.
Marques1,
Pedro
Amorim1,
Leonel
Gordo2,
Ana
Moreno1 and
Alexandra
A.
Silva1, 2
-
1
Portuguese Institute of Ocean and Atmosphere (IPMA), Portugal
-
2
Centro de Estudos do Ambiente e do Mar, Faculdade de Ciências da Universidade de Lisboa, Portugal
Atlantic chub mackerel (Scomber colias) is a middle-size pelagic species which mostly inhabits warm waters, distributed along the Eastern Atlantic coasts from South Africa to the Bay of Biscay, and occupying mainly the continental shelf and the upper slope depths. Population abundance and distribution in Portuguese waters significantly fluctuate over time, with maximum values observed in the middle of the last 3 decades. In this area, it is fished mainly by the purse seine and the artisanal multi-gear fleets. Landings have increased since the mid-2000’s in Iberian waters, which represented in 2012 to 2017 1/4 to 1/3 of the landings in the Portuguese mainland (from 19000 ton. in 2017 to 45000 ton. in 2015). This rise is possibly correlated with the significantly decrease of sardine availability, the increase in abundance of chub mackerel, and a growing economical (canning industry, feeding of aquaculture species) and gastronomical interest on the species. However, landings are not regulated, the species being solely subjected to a minimum landing size and general technical restrictions, and despite the importance of this resource, no formal scientific assessment and advice are undertaken at present, with no guarantee that the exploitation rate is sustainable with the current catches estimates.
Additionally, the dynamics of this species within the pelagic ecosystem in Atlantic Iberian waters are poorly known. Most chub mackerel caught in Iberia are young individuals (up to 2-3 years old), older fish being rarely observed in surveys and from the commercial fleet. Spawning, recruitment and nursery areas are not clearly identified, and the connectivity of individuals between adjacent Iberian areas and with the Moroccan waters is not known.
The understanding of the reproductive dynamics and growth pattern of chub mackerel is relatively limited; there are no estimations of the species spawning biomass and/or reproductive potential, and age determination is uncertain due to the presence of false rings.
In view of the above, the objective of this work was to contribute to building knowledge on the growth and on the reproductive biology of chub mackerel off Portuguese waters.
During this study, chub mackerel samples were collected bi-monthly during 2012 in Peniche, and in 2014-2015 in Matosinhos harbours. Sagittal otoliths edge analysis (interpretation of whether the edge zone under formation is opaque or translucent) was performed in order to verify the existence of an annual growth pattern by examining the growing edge type of otoliths along time. The progression of diameter frequency was analysed in a subset of otoliths to identify different age groups. From the results obtained, the seasonal pattern of the otolith increments was described, growth taking place mainly during spring and summer months. Age was determined from counts of opaque (transmitted light) annual growth zones, the growth pattern was analysed, and the growth parameters were estimated for the chub mackerel off the West coast.
Samples collected regularly in 2014-2016 from the commercial fleet in both Matosinhos and Sesimbra harbours and during the winter and spring acoustic surveys in 2014-2018, were used to investigate chub mackerel reproductive biology, by means of the analysis of individual macroscopical and microscopical information (from histological preparations of preserved gonads). The results obtained allowed to microscopically determine the size at first maturity of chub mackerel in the Western Atlantic Portuguese waters (L50 = 20.57 ± 0.52 cm) and to describe the seasonal dynamics of the reproductive activity, key input to evaluate the spawning population (the fraction which is to contribute to the reproductive output), chub mackerel reproducing mostly during winter and spring months, though a very high proportion of inactive females were observed even at peak spawning off the West coast.
Additionally, chub mackerel individual biological data collected during the Portuguese Winter and Spring Groundfish and Acoustic surveys for the period 2000-2018 was analysed to investigate possible geographical differences in reproductive activity and growth pattern.
The above results were compared to and discussed in relation to the available similar information in adjacent geographical areas, with the view of attempting to understand the species dynamics in Atlantic Iberia, the final aim being to improve the scientific information for an accurate data-based assessment and management for this marine exploited resource.
Acknowledgements
Samples were obtained within the framework of the National Biological Sampling Program (PNAB, EU/DCF). Thanks are due to all colleagues involved in the biological sampling (IPMA) and in the histological processing (IPMA, FCUL).
Keywords:
Atlantic chub mackerel,
reproductive activity,
Growth pattern,
Histology,
otoliths analysis,
Geographical differences
Conference:
XX Iberian Symposium on Marine Biology Studies (SIEBM XX) , Braga, Portugal, 9 Sep - 12 Sep, 2019.
Presentation Type:
Oral Presentation
Topic:
Fisheries, Aquaculture and Biotechnology
Citation:
Nunes
C,
Silva
AV,
Feijó
D,
Soares
E,
Porfírio
A,
Morais
D,
Correia
G,
Da Conceição
P,
Silva
M,
Chaves
C,
Marques
VJ,
Amorim
P,
Gordo
L,
Moreno
A and
Silva
AA
(2019). Atlantic chub mackerel (Scomber colias) growth and reproduction off the Portuguese coast in relation to the population dynamics.
Front. Mar. Sci.
Conference Abstract:
XX Iberian Symposium on Marine Biology Studies (SIEBM XX) .
doi: 10.3389/conf.fmars.2019.08.00022
Copyright:
The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers.
They are made available through the Frontiers publishing platform as a service to conference organizers and presenters.
The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated.
Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed.
For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions.
Received:
19 Jun 2019;
Published Online:
27 Sep 2019.
*
Correspondence:
Mx. Cristina Nunes, Portuguese Institute of Ocean and Atmosphere (IPMA), Lisbon, Portugal, cnunes@ipma.pt