The status of redfish (S. mentella and S. fasciatus) in Divisions 3LN at present and the likelihood its follow up in the near future (under the ongoing the Management Strategy or a status quo TAC scenario)

There are two species of redfish in Divisions 3L and 3N, the deep-sea redfish (Sebastes mentella) and the Acadian redfish (Sebastes fasciatus) that have been commercially fished and reported collectively as redfish in fishery statistics. Both species, occurring on Div. 3LN and managed as a single stock, don’t belong to isolated local populations but, on the contrary, are part of a large Northwest Atlantic complex ranging from the Gulf of Maine to south of Baffin Island. The ASPIC assessment of this stock is based on the logistic form of a non-equilibrium surplus production model (Schaeffer, 1954; Prager, 1994), adjusted to a standardized catch rate series (Power, 1997) and to all stratified-random bottom trawl surveys conducted in various years and seasons in Div. 3L and Div. 3N from 1978 onwards. Both CPUE and surveys were used with all observations within each series. The 2018 assessment proceed on the threshold of the new 2014 approach, the main features of the previous input framework were kept, with MSY fixed at 1960-1985 average catch and the rest of the approved 2014 assessment framework updated. Despite its poor performance the 3L Spanish survey has been kept in the analysis due to its high correlation with the autumn 3LN Canadian survey, one of the two backbone series of the assessment. ASPIC results confirm a stable stock from the 1960’s to the first half of the 1980’s, sustaining an average yield of 21 000t. Stock declined with a sudden rise of the catch over the late 1980’s first half of the 1990’s, and started to gradually recover after catches fell to a residual level when the stock collapse. The maximum observed sustainable yield (MSY) of 21 000 t can be a long term sustainable yield if fishing mortality stands at 0.11/year, exploiting a correspondent Bmsy at 187 000 t. From assessment results there is a high probability (CL’s 80%) that the stock was at the beginning of 2018 above Bmsy, after crossing 2017 under a fishing mortality most likely below 34% Fmsy

A Revised Update of the 2014 ASPIC Assessment of Redfish (S. mentella and S. fasciatus) in Divisions 3LN (how the the stock is coping with the actual Management Strategy and its likely impact on the next coming years).

There are two species of redfish in Divisions 3L and 3N, the deep-sea redfish (Sebastes mentella) and the Acadian redfish (Sebastes fasciatus) that have been commercially fished and reported collectively as redfish in fishery statistics. Both species, occurring on Div. 3LN and managed as a single stock, don’t belong to isolated local populations but, on the contrary, are part of a large Northwest Atlantic complex ranging from the Gulf of Maine to south of Baffin Island. The present ASPIC assessment of this stock is based on the logistic form of a non-equilibrium surplus production model (Schaeffer, 1954; Prager, 1994), adjusted to a standardized catch rate series (Power, 1997) and, for the first time, to all stratified-random bottom trawl surveys conducted in various years and seasons in Div. 3L and Div. 3N from 1978 onwards. Both CPUE and surveys were used with all observations within each series. In order to proceed on the threshold of the new 2014 approach, and taking into account that since then no substantial changes appear to have occurred on the state of the stock, the main features of the previous input framework were kept, with MSY fixed at 1960-1985 average catch and the rest of the approved 2014 assessment framework updated. The 3L Spanish survey, the only ongoing survey so far outside the analysis, has now been successfully included on this assessment framework (relative inter-quartile range from bootstrap analysis for the last two assessments highlight the higher consistence of most of the 2016 assessment results when compared with the ones from 2014). ASPIC assessment results confirm a stable stock from the 1960’s to the first half of the 1980’s, sustaining an average yield of 21 000t. Stock declined with a sudden rise of the catch over the late 1980’s first half of the 1990, and increased since then, after catches fell to a residual level with the stock collapse. Assessment results also confirm that the maximum observed sustainable yield (MSY) of 21 000 t can be a long term sustainable yield if fishing mortality stands at 0.11/year, exploiting a correspondent Bmsy at 190 000 t. 2 There is a very high probability that the stock was at the beginning of 2016 at or above Bmsy , after crossing 2015 under a fishing mortality most likely at or below 50% Fmsy. There is also a very high probability that catch on 2016 at 10 400 t TAC and on 2017 and 2018 at the predicted increases approved in the 2014 Risk‐Based Management Strategy for 3LN Redfish, will keep fishing mortality on 2018 below Fmsy and biomass at the beginning of 2019 above Bmsy.Postprint0,000

The status of redfish (S. mentella and S. fasciatus) in Divisions 3LN and two medium term scenarios (when recruitment is low, Risk Based Management Strategy or common sense?)

There are two species of redfish in Divisions 3L and 3N, the deep-sea redfish (Sebastes mentella) and the Acadian redfish (Sebastes fasciatus) that have been commercially fished and reported collectively as redfish in fishery statistics. Both species, occurring on Div. 3LN and managed as a single stock, don’t belong to isolated local populations but, on the contrary, are part of a large Northwest Atlantic complex ranging from the Gulf of Maine to south of Baffin Island. The ASPIC assessment of this stock is based on the logistic form of a non-equilibrium surplus production model (Schaeffer, 1954; Prager, 1994), adjusted to a standardized commercial catch rate series (Power, 1997) and to all stratified-random bottom trawl surveys conducted in various years and seasons in Div. 3L and Div. 3N from 1978 onwards. Both CPUE and surveys were used with all observations within each series. The 2020 assessment proceed on the threshold of the new 2014 approach, with MSY fixed at 1960- 1985 average catch and the rest of the approved 2014 assessment framework updated. ASPIC results present a stock stable from the 1960’s to the first half of the 1980’s while sustaining an average yield of 21 000t. Stock declined with a sudden rise of the catch over the late 1980’s first half of the 1990’s, and started to gradually recover after catches fell to a residual level in response to stock collapse. The maximum observed sustainable yield (MSY) of 21 000 t is linked to a Fmsy at 0.11/year and a Bmsy at 185 000 t. There is a high probability (>90%) that the stock was at least 38% above Bmsy at the beginning of 2020, after crossing 2019 under a fishing mortality not higher than 46% Fmsy

An assessment of beaked redfish (S. mentella and S. fasciatus) in NAFO Division 3M, from a biological based approach to recent levels of natural mortality (2011-2016)

The 3M redfish assessment is focused on the beaked redfish, regarded as a management unit composed of two populations from two very similar species: the Flemish Cap S. mentella and S. fasciatus. The reason for this approach is the historical dominance of this group in the 3M redfish commercial catch until 2005. However a new golden redfish fishery (S. marinus) started on September 2005 on shallower depths of the Flemish Cap bank above 300m, and the Flemish Cap cod fishery reopened in 2010. These new realities implied a revision of catch estimates, in order to split recent redfish commercial catch and by-catch from the major fleets on Div. 3M into golden (S. marinus) and beaked (S. mentella and S. faThe Extended Survivor Analysis assessment used as tuning file the 1989-2016 EU survey abundance at age matrix included in a revised input framework. Continuing pressure over Flemish Cap redfish stocks by cod predation, at levels higher, or much higher, than the levels prior to 2006 lead to higher natural mortalities since then. In order to include an independent approach to natural mortality in the sensitivity M framework, for the more recent years (2011-2016) natural mortality has been estimated from a number of different biological models, some size/age-independent and others size/age-dependent. These different estimates were arranged in two sets and tuned to survey at age data. A natural mortality of 0.1 on 2015-2016 and the natural mortalities adjusted on previous assessments were found to be the most suitable option to M input. A 2017-2013 retrospective XSA was performed, confirming the consistency of the present with preceding results as regards stock biomass, female spawning biomass and fishing mortality.sciatus) redfish catches. Above average year classes and high survival rates allowed a rapid growth of biomass and abundance 2003 onwards, pulling the stock to a 2008-2010 high. Since 2009 abundance went down for causes other than fishing, being still above the 1990’s low in 2016. By the turn of the decade stock biomass and female spawning biomass (SSB) shown marginal declines as well, but reversed on 2011-2012. Individual growth of survivors and low fishing mortalities sustained stock biomass and SSB at high levels till 2015-2016. Recruitment at age 4 increased from 2002 till 2006 and was maintained at a maximum level till 2009. Recruitment declined since then and is kept on 2015-2016 at the low of the weak year classes from the 1990’s, while SSB is still well above the size that originated the high 2002-2006 recruitments. Despite the significant decline so far natural mortality has not flattened yet. If natural mortality and fishing mortality stay at their most recent levels, the actual high of female spawning biomass can hold on 2018-2019. But on the long term it will be natural mortality, namely over pre recruited ages, to determine the future of beaked redfish as a fishery resource. On 2015 STACFIS remind that projections are based in the assumption that natural mortality stay at its most recent level on the present year and at least on the two next coming years. And that, taking into account the uncertainty on the present and future level of natural mortality, its impact on female spawning stock biomass at the end of any projection is unknown. On 2017 these constraints are still in place, and therefore short and medium term projections are not presented.Versión del edito

GadCap: A GADGET multispecies model for the Flemish Cap cod, redfish and shrimp.

Since late 1980s, the demersal community of Flemish Cap (NAFO area 3M) has experienced large variations (including the collapse) in the abundance and population structure of its main fishing resources: cod Gadus morhua, redfish Sebastes sp. and shrimp Pandalus borealis, with alternation in their dominant role in the ecosystem. GadCap is an EU project dealing with the development of a GADGET multispecies model for the Flemish Cap cod, redfish and shrimp, as part of the NAFO roadmap for the EAF. The effect of fishing, trophic interactions (including cannibalism) and water temperature in the dynamic of these three major fishing resources has been modeled. The results highlight the interdependent dynamic of these stocks, and reveals strong interactions between recruitment, fishing and predation (including cannibalism), with marked changes in their relative importance by species-age-length over time. The multispecies model shows that disregarding the species interactions would lead to serious underestimates of natural mortality, overestimations of the exploitable biomass, and highlights the need to move beyond single-species management in this highly coupled ecosystem. Preliminary estimates of total SSB and MSY, under different combinations of fishing mortality for all the three stocks, are also presented.Postprint0,000

Social Networks Shape the Transmission Dynamics of Hepatitis C Virus

Hepatitis C virus (HCV) infects 170 million people worldwide, and is a major public health problem in Brazil, where over 1% of the population may be infected and where multiple viral genotypes co-circulate. Chronically infected individuals are both the source of transmission to others and are at risk for HCV-related diseases, such as liver cancer and cirrhosis. Before the adoption of anti-HCV control measures in blood banks, this virus was mainly transmitted via blood transfusion. Today, needle sharing among injecting drug users is the most common form of HCV transmission. Of particular importance is that HCV prevalence is growing in non-risk groups. Since there is no vaccine against HCV, it is important to determine the factors that control viral transmission in order to develop more efficient control measures. However, despite the health costs associated with HCV, the factors that determine the spread of virus at the epidemiological scale are often poorly understood. Here, we sequenced partial NS5b gene sequences sampled from blood samples collected from 591 patients in São Paulo state, Brazil. We show that different viral genotypes entered São Paulo at different times, grew at different rates, and are associated with different age groups and risk behaviors. In particular, subtype 1b is older and grew more slowly than subtypes 1a and 3a, and is associated with multiple age classes. In contrast, subtypes 1a and 3b are associated with younger people infected more recently, possibly with higher rates of sexual transmission. The transmission dynamics of HCV in São Paulo therefore vary by subtype and are determined by a combination of age, risk exposure and underlying social network. We conclude that social factors may play a key role in determining the rate and pattern of HCV spread, and should influence future intervention policies