Linking sardine recruitment in coastal areas to ocean currents using surface drifters and HF radar: a case study in the Gulf of Manfredonia, Adriatic Sea
<p>Understanding the role of ocean currents in the recruitment of commercially and ecologically important fish is an important step toward developing sustainable resource management guidelines. To this end, we attempt to elucidate the role of surface ocean transport in supplying recruits of Eu...
| Main Authors: | , , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2018-11-01
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| Series: | Ocean Science |
| Online Access: | https://www.ocean-sci.net/14/1461/2018/os-14-1461-2018.pdf |
| Summary: | <p>Understanding the role of ocean currents in the recruitment of commercially
and ecologically important fish is an important step toward developing
sustainable resource management guidelines. To this end, we attempt to
elucidate the role of surface ocean transport in supplying recruits of
European sardine (<i>Sardina pilchardus</i>) to the Gulf of Manfredonia, a
known recruitment area in the Adriatic Sea. Sardine early life history stages
(ELHSs) were collected during two cruises to provide observational estimates
of their age–size relationship and their passive pelagic larval duration
(PPLD). We combine these PPLDs with observations of surface ocean currents to
test two hypotheses: (1) ELHSs are transported from remote spawning areas (SAs)
by ocean currents to the Gulf of Manfredonia; (2) sardines spawn locally and
ELHSs are retained by eddies. A historical surface drifter database is used to
test hypothesis 1. Hypothesis 2 is tested by estimating residence times in
the Gulf of Manfredonia using surface drifters and virtual particles
trajectories that were computed from high-resolution observations of surface
currents measured by a high-frequency (HF) radar network. Transport to the
Gulf of Manfredonia from remote SAs seems more likely than local spawning and
retention given a mismatch between observed PPLDs of 30–50 days and
relatively short (<span class="inline-formula"><10</span>-day) average residence times. The number and
strength of connections between the gulf and remote SAs exhibit a strong
dependence on PPLD. For PPLDs of 20 days or less, the gulf is connected to
SAs on the western Adriatic coast through transport in the Western Adriatic
Current (WAC). SAs on the east coast are more important at longer PPLDs. SAs
in the northern and central Adriatic exhibit weak connections at all PPLD
ranges considered. These results agree with otolith microstructure analysis,
suggesting that the arrival of larvae in the gulf is characterized by
repeated pulses from remote SAs. This is the first attempt to describe the
processes related to Lagrangian connection to, and retention in, the Gulf of
Manfredonia that will be complemented in the future using validated numerical
ocean models and biophysical models.</p> |
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| ISSN: | 1812-0784 1812-0792 |