27 research outputs found
North Atlantic oscillation affects the physical condition of migrating bullet tuna Auxis rochei (Risso, 1810) from the Western Mediterranean Sea
Climate oscillations exert direct control over the environment in which they occur and may influence the
physical condition of migratory marine species, such as tuna, as reported by several authors. The main aim of
thisstudywastoexploretheassociationbetweenthepotentialeffectsoftheNorthAtlanticOscillation(NAO)on
thefitness condition of bullet tuna (Auxis rochei) migrating to the Spanish Mediterranean Sea. A total of 2357
length-weight pairs of data obtained from individuals collected on the Spanish Mediterranean coast were analysed.
A non-parametric Spearman test was used to investigate correlations between the atmospheric oscillation
indexes and two physical condition indexes. The results suggest that, in general, positive phases of the NAO
index improve the physical condition offish migrating to spawning grounds in the Mediterranean Sea. These
results could be explained by changes in the dominant winds, which could favour pre-spawning migration, and
by nutrients availability, which guarantees their recovery after the spawning period.En prens
BRIEF UPDATE ON THE SATELLITE TAGGING OF ATLANTIC SWORDFISH
This paper provides a brief update of the study on habitat use for swordfish, developed within the
working plan of the Swordfish Species Group of ICCAT. A total of 9 miniPAT tags have been
deployed by observers on Portuguese and Spanish vessels and the Uruguayan research cruise in
the North and South Atlantic. Data from eight tags/specimens are available, four specimens
suffered from post-release mortality and one individual tag pop-up date has not occurred yet.
These preliminary results showed swordfish moved in several directions, travelling considerable
distances. Swordfish spent most of the daytime in deeper waters, being closer to the surface
during night-time. The main plan for the next phase of the project is to continue the tag
deployment during 2020 in several regions of the Atlantic Ocean and Mediterranean SeaEn prens
Preliminary management strategy evaluation for blue shark in the Indian Ocean using a data-limited approach
In tuna-RFMOs there has been an effort to move to quantitative stock
assessments for pelagic sharks, especially for the main species such as
blue shark Prionace glauca. In IOTC, blue shark was last assessed in
2017 with the use of an integrated length-based age-structured model
(SS3). This paper now presents a preliminary exercise with data-limited
Management Strategy Evaluation (MSE) to test options for different
potential management procedures (MPs), using the data-limited methods
toolkit (DLMtool). Reference points have not yet been adopted for sharks
in IOTC, so for this exercise we set some tentative reference points noting
that those can be updated in the future as needed. Eighty-nine MPs were
evaluated with 9 considered potentially acceptable. Options and tradeoffs between those MPs are shown and described in the paper. We have
focused mainly on trade-offs between biomass and yield, but according
to the management objectives agreed other performance metrics can be
applied. Even thought this is a preliminary exercise at this point, we hope
that it provides initial thoughts and opens the discussion for the
advancement of the blue shark management and conservation in the
Indian Ocean
Intraoperative radiotherapy in the multidisciplinary treatment of bone sarcomas in children and adolescents
From September 1984 to December 1989, 38 patients of pediatric age with localized bone sarcomas received intraoperative radiotherapy (IORT) as part of a multidisciplinary treatment program. The age ranged from 6 to 21 years. The tumor histologies were 22 osteosarcomas and 16 Ewing's sarcomas. Thirty-four had initial primary disease (90%) and 4 were treated for local recurrence (10%). IORT was used on 32 untreated patients and in 6 previously treated with external beam radiotherapy (EBR). The IORT field included the surgically exposed tumor bed area. Single radiation doses ranging from 10 to 20 Gy were delivered, using 6-20 MeV electron beams. The median follow-up time for the entire group is 25 months (2-65+ months). The projected 5-year disease-free and overall survival rates are 65% and 69%, respectively. One patient developed a local recurrence in each histological group: one chondroblastic osteosarcoma and one cervical Ewing's sarcoma. Six patients died from metastatic progression: 3 initially recurrent tumors and three primary disease cases. Severe neuropathy and soft tissue necrosis were seen in some patients as IORT related complications. IORT is a feasible technique to be integrated in multidisciplinary programs that may promote local control in pediatric and adolescent patients with bone sarcomas. Peripheral nerves are dose-limiting tissue structures for IORT
Environmental variablity in three major Mediterranean tuna spawning grounds.
We propose four different environmental indicators, three related to temperature variability in
three major spawning grounds of tuna species in the Mediterranean, and one related to the sea
surface salinity variability in the Balearic Sea. These oceanographic indicators show the
annual variability of environmental parameters affecting growth and survival of tuna eggs and
larval. The indicators are intended to provide quick access to assessment working groups and
fisheries scientist to identify potentially anomalous year
ASSESSING THE SPAWNING STOCK BIOMASS OF ALBACORE (THUNNUS ALALUNGA) IN THE WESTERN MEDITERRANEAN SEA FROM A NON-LINEAR LARVAL INDEX (2001-2019)
Larval abundance indices express retrocalculated abundances of larval densities at hatching
time. They provide a proxy for assessing spawning stock biomass and are applied to assess
population status of various species in the Gulf of Mexico and in the Balearic Sea. Recently, the
methodological approach to calculate the indices was improved to accommodate for non-linear
responses of environmental effects on catchability. This improved methodology is routinely
applied in the Balearic Sea to assess the bluefin tuna (Thunnus thynnus) spawning stock
biomass. Here we apply the same methodology to update the larval index of albacore (Thunnus
alalunga) from surveys conducted from 2001 to 2019 in the Balearic Sea, the most relevant
spawning ground of this species in the Western Mediterranean. Albacore larval abundances
show a decreasing trend and significant lower abundances from 2013 onwards, despite a slight
recovery between 2016 and 2017. This larval index, standardized for gears, sampling coverage,
salinity, date and sea surface temperature, provides information on the dynamics of the western
Mediterranean stock of albacore, which is considered a data poor stock.En prens
LARVAL HABITATS AND CATCHES OF SWORDFISH (XIPHIAS GLADIUS) IN THE BALEARIC ISLANDS (2001-2020): OCEANOGRAPHIC DRIVERS AND OPPORTUNITIES FOR RESEARCH
Since 2001, ichthyoplankton and hydrographic surveys directed to tuna species have been
conducted in the Balearic Islands, a main tuna spawning ground in the Mediterranean. These
campaigns provide today key information about the interannual changes on larval abundances
for Bluefin tuna and albacore, also allowing the investigation of the early-life ecology of various
species. The Balearic Islands have been identified as a prominent oceanographic retention area
within the western Mediterranean as well as the main spawning area for tuna species. Hence, the
regular ichthyoplankton surveys become an opportunity to increase the knowledge of those
species whose pelagic early-life stages are encountered during the summer in this area. This is
the case of swordfish (Xiphias gladius). Here we analyse the possibility of applying those surveys
to investigate the early life ecology of the Mediterranean swordfish, exploring the interannual
changes on larval abundances and the hydrographic preferences of larval habitatsEn prens
Local indicators for global species: Pelagic sharks in the tropical northeast Atlantic, Cabo Verde islands region.
Pelagic sharks are an important bycatch in pelagic fisheries, especially for drifting longlines targeting swordfish. In the Cabo Verde Archipelago (tropical NE Atlantic), pelagic shark catches can reach a significant proportion of the total catches. Due to the increased concern on the status of pelagic shark species, this study was developed to enhance the current knowledge of those sharks in the Cabo Verde region in comparison to the adjacent areas, especially associated with European Union (EU) pelagic longline fishing activity. Stock status indicators for the two main species, blue shark (Prionace glauca) and shortfin mako (Isurus oxyrinchus), were developed, based on fisheries data from logbooks and onboard scientific observers, including analysis of size frequency distributions and standardized catch-per-unit-of-effort (CPUE) indexes over time. The standardized CPUEs have been stable or increasing for both species in the past 10 years, indicating no signs of local depletion. In terms of sizes, the blue shark catch is composed mainly of adults, which can be a sign of a stable population. On the contrary, the catch of shortfin mako is composed mainly of juveniles, which in conjunction of a decrease of mean size might be a cause of concern, highlighting possible overfishing on the species in the region. Thirty satellite tags, 25 archival miniPATs and 5 SPOT GPS, were deployed in the Cabo Verde Exclusive Economic Zone (EEZ), showing that those species are highly mobile. The biomass and size distributions were modeled with spatial and seasonal models (GAMs) identifying locations where juveniles are predominantly concentrated and that should be prioritized for conservation. This work presents new information on the status of pelagic sharks in the Cabo Verde region in the context of those highly migratory species, and can now be used to promote more sustainable fisheries in the region
Report on the 2020 ICCAT workshop on small tunas biology studies for growth and reproduction
This report describes the 2020 ICCAT workshop on small tunas biology studies for growth and
reproduction, hosted by the Instituto Español de Oceanografía, Málaga, Spain. The major
objectives of the workshop were: 1) starting the creation of ageing and reproduction reference
sets and, 2) providing more training for the ongoing sample collection and processing to the
teams involved in these studies. As approved by the SCRS in 2017, the Small Tuna Species
Group intersessional meeting decided to prioritize the collection of biological samples aiming
at growth, maturity and stock structure studies on three species: little tunny (Euthynnus
alletteratus), Atlantic Bonito (Sarda sarda) and wahoo (Acanthocybium solandri), based on
their economic importance and the lack of knowledge on their biology. This work will
contribute to the next major advance in the assessment of these three species
North Atlantic oscillation affects the physical condition of migrating bullet tuna Auxis rochei (Risso, 1810) from the Western Mediterranean Sea
Climate oscillations exert direct control over the environment in which they occur and may influence the
physical condition of migratory marine species, such as tuna, as reported by several authors. The main aim of
thisstudywastoexploretheassociationbetweenthepotentialeffectsoftheNorthAtlanticOscillation(NAO)on
thefitness condition of bullet tuna (Auxis rochei) migrating to the Spanish Mediterranean Sea. A total of 2357
length-weight pairs of data obtained from individuals collected on the Spanish Mediterranean coast were analysed.
A non-parametric Spearman test was used to investigate correlations between the atmospheric oscillation
indexes and two physical condition indexes. The results suggest that, in general, positive phases of the NAO
index improve the physical condition offish migrating to spawning grounds in the Mediterranean Sea. These
results could be explained by changes in the dominant winds, which could favour pre-spawning migration, and
by nutrients availability, which guarantees their recovery after the spawning period.S