Temporal variability of spawning in the sea urchin Paracentrotus lividus from northern Spain
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1
Dirección General de Pesca Marítima., Centro de Experimentación Pesquera., Spain
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2
Dirección General de Pesca Marítima., Centro de Experimentación Pesquera. Dirección General de Pesca Marítima., Spain
Introduction
Paracentrotus lividus is the most exploited echinoid in Europe, in countries such as Ireland, France, Italy, Greece, Portugal and Spain. In the latter, it is mainly harvested in the northwest (Galicia), north (Asturias, Cantabria and Basque Country), northeast (Catalonia) and south (Andalusia) where fishing activities regulations depend on the regional government. In Asturias, there is a strong tradition of consumption and harvesting of sea urchins. Professional and recreational fishermen harvest individuals with a minimum size of captured (test diameter >5.5 cm) on intertidal areas. There is a limited catch only for nonprofessional fishermen (5 kg per day) and harvesting is no allowed in subtidal areas. However, a decreased in the wild populations was observed, especially on the west coast of Asturias. Thus, a closed season (from April to December) is included in the regulatory measures since 2013.
The current situation of sea urchin fishery is influenced by harvesting methods and also by habitat transformation and environmental changes. Such a situation emphasizes the need for more efficient management tools to reach sustainable resources and improved fisheries. The objective of this study was to provide a baseline for resource managers to evaluate and predict differences in reproduction caused by harvesting strategies and possible environmental changes.
Material and methods
The study was performed on Paracentrotus lividus adults from an intertidal population on the west coast of Asturias (Spain). In this area, the shore is rocky and exposed, and the pools are inundated daily. The pools are covered with the red algae Litophyllum incrustans and other calcareous algae and the main source of food is drifting brown algae (laminarians).
Thirty individuals of commercial size were collected monthly from March 2006 to June 2008, and during spring 2009 (March-June). The sea urchins were measured, wet weighed and dissected. Then, the gonads were wet weighed and the gonad index (GI) was calculated as the ratio of the gonad wet weight to the whole-body wet weight given as a percentage.
On each sampling date, ten gonads (from five females and five males) were collected and preserved in Davidson fluid for histological examination. The reproductive state of the urchins was then assessed following the descriptions of Byrne (1990) who stablished six stages of ovarian and testis growth: recovery, growing, premature, mature, spawned and spent.
In addition, a monthly record of the sea surface temperature and phytoplankton abundance (chlorophyll a) were obtained during the sampling period.
Results and conclusions
The reproductive cycle of P. lividus on the west coast of Asturias showed a well-defined annual pattern. The GI temporal trend indicated a rapid increase in spring with maxima ranging from 15.7 to 17.4% in April-May over the four years studied. Thereafter, the spawning took place and GI decreased abruptly, reaching minimum values in August (3.9 to 5.2%).
The GI trend is correlated to the state of maturation of the gonads. In the maturation phase (spring and early summer), the highest GI corresponds to a gonad filled with ova and spermatozoa. During the spent phase (late summer and early autumn), gonads devoid of sexual cells have the lowest GI values. And the growth phase (late autumn and winter), gonads accumulate reserve material and GI increases.
Seasonal environmental events played an important role in controlling reproduction and although the overall pattern was consistent, there were interannual differences. The time when spawning started differed between years. The spawning in 2006 began approximately a month earlier than in the subsequent three years. The maximum sea temperatures recorded in August appear to coincide with the end of spawning. And in 2008, probably gametogenesis started sooner due to a warmer winter.
In the studied intertidal population, GI reflected the reproductive cycle of the species and the spawning period was identified, in order to determine the yield of local population and also the best time to harvest the sea urchin.
References
Byrne, M. 1990. Annual reproductive cycles of the commercial sea urchin Paracentrotus lividus from an exposed intertidal and a sheltered subtidal habitat on the west coast of the Ireland. Marine Biology, 104: 275-289.
Keywords:
Paracentrotus lividus,
reproductive cycle,
Histology,
sea urchin,
Harvesting
Conference:
XIX Iberian Symposium on Marine Biology Studies, Porto, Portugal, 5 Sep - 9 Sep, 2016.
Presentation Type:
Poster Presentation
Topic:
4. FISHERIES, AQUACULTURE AND BIOTECHNOLOGY
Citation:
De La Uz
S,
Carrasco
JF and
Rodríguez
C
(2016). Temporal variability of spawning in the sea urchin Paracentrotus lividus from northern Spain.
Front. Mar. Sci.
Conference Abstract:
XIX Iberian Symposium on Marine Biology Studies.
doi: 10.3389/conf.FMARS.2016.05.00203
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Received:
29 Apr 2016;
Published Online:
03 Sep 2016.
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Correspondence:
Ms. Silvia De La Uz, Dirección General de Pesca Marítima., Centro de Experimentación Pesquera., Castropol, Asturias, 33760, Spain, silviadelauz@gmail.com
Mr. Jose F Carrasco, Dirección General de Pesca Marítima., Centro de Experimentación Pesquera. Dirección General de Pesca Marítima., Gijón, Asturias, 33212, Spain, JOSEFRANCISCO.CARRASCOFIDALGO@asturias.org