Argentine red shrimp

INIDEP (Instituto Nacional de Investigación y Desarrollo Pesquero) is the public body responsible for the assessment of the fishery resources in the Argentine Sea. INIDEP gives advice to the Consejo Federal Pesquero (CFP) and Subsecretaría de Pesca y Acuicultura (SSPyA) on the sustainable use of these resources, with the aim of preserving the marine ecosystem.

P. muelleri is characterized by a relatively short life cycle and high and variable growth rate, great reproductive potential, and usually an almost total replacement of available biomass between two successive fishing years (Bertuche & Fischbach, 1998). The great fluctuations in the annual recruitment generates variability in the biomass abundance available for the fleet, putting the resource at permanent risk of overfishing in the growth phase and in the recruitment phase (Bertuche & Fischbach, 1998; Fischbach & Bertuche, 1999; De la Garza, 2006).

INIDEP run a Shrimp Project, with a basis in the Precautionary Principle (UNCED, Rio de Janeiro1992), (Bertuche et al., 2000), aiming to contribute to the conservation of the shrimp stock, anticipating critical situations and applying fisheries management tools that avoid recruitment overfishing. Researchers are involved in this project since the 80s (nowadays 7 researchers comprise the group) in response to the demand for scientific knowledge on the population dynamics of P. muelleri. Since the demands from the fishing sector and the administration have increased, the project now also studies and generates estimators of future productivity scenarios and management and harvesting strategies that consider the extreme variability in yearly recruitment, the short life cycle and the high and variable growth for this species.

The harvesting strategy is based on an ongoing assessment of the daily CPUE (catches per hour and catches per day) as a proxy of shrimp abundance, the length frequency of the catches and the shrimp/hake ratio. This information allows for the periodic generation of estimates of future production scenarios and management tools appropriate to the variability of the resource. On the basis of the information obtained in real-time, pragmatic and quick decisions are proposed as required by the ecology of the resource, such as dynamic temporal and spatial closures that maximize the potential for resource renewal (Bertuche et al, 2000).

The INIDEP on board observers program evaluates the relative abundance of the stock through shrimp monthly average catch per day (CPD) expressed as kilograms per fishing day, which is considered to be more reliable than the captures per fishing hour based on logbooks (which is also monitored). Landings are equivalent to capture since the discarded shrimp is negligible (Fischbach et al, 2009; Fischbach & Bertuche, 2015). Thus, the yield is expressed in terms of kg of shrimp caught by fishing day and assumes the CPD as a proxy of the shrimp abundance. The CPUE, expressed as kilograms per fishing hour, is based on the logbooks filled out by the captains of the fishing vessel and it is also monitored on a daily basis during the fishing season. The relationship between catches of hake and shrimp per fishing hour (hake/shrimp ratio) is a key indicator for INIDEP for recommending the closure of a fishing area; this ratio goes from ~0.09 at the beginning of the fishing season to almost 1 at the end of the fishing season, which means that equal kilograms of shrimp and hake are captured per hour.

The Patagonian red shrimp fishery in Argentina has been managed since its inception as a single biological stock unit (Boschi, 1989). Based on the research done by INIDEP the processes of reproduction, recruitment and growth in P. muelleri occur continuously but variably in time and space. Therefore it is not possible to identify a cohort or real stock unit to follow for a long period of time, so the concept of stock unity and cohort monitoring could not be applied (Bertuche & Fischbach, 1998). Further research suggested the existence of three ecological subunits of reproduction and growth: Rawson’s coastline area (43° 30’ S), and the northern (45° S) and southern (47° S) areas of the San Jorge Gulf, in which spawning occurs at different times of the year (De Carli et al. 2012). A mark, release and recapture program of P. muelleri in the San Jorge Gulf carried out by INIDEP allowed the identification of two migration routes. One of these routes is used by a portion of the population that was born and grows in the southern part of the gulf, remaining in this area and possibly also reproducing there (De Carli, et al 2012).

Specifically related with the red shrimp fishery, the Crustaceans Fisheries Program in INIDEP carries out several projects to determine the relative abundance and distribution of breeding individuals, the stages of gonadal development, the distribution and density of eggs and larvae, the female size at maturity and indexes of potential and the relative fertility of the species. The program also provides information on the environmental variables related to the processes of recruitment and biomass abundance available for fishing. (Fernández et al., 2001; 2002; 2003; Fernández and Macchi, 2004; 2005; 2006; 2007; 2008; 2009; 2010; 2012; 2014). Unfortunately the scientific survey conducted annually with INIDEP oceanographic vessels has been suspended since April 2014 due to an unsolved trade union claim.

Besides the scientific surveys, INIDEP conducts an ongoing shrimp fishery assessment on fishing vessels with on board observers which includes the collection of fishery data (CPUE, CPD, size frequency, bycatch and discards) for the estimation of shrimp biomass relative abundance and the hake/shrimp ratio during the fishing season. The management body (Consejo Federal Pesquero – CFP) authorizes INIDEP to run the initial assessment surveys for the opening of the fishing season. This is done on commercial fishing vessels under INIDEP technical considerations (including number of vessels, area surveyed and days per area). As the shrimp stock migrates, new areas are petitioned to be opened by the fishing sector; INIDEP survey the new area and recommends its opening or not based on CPD and shrimp size frequency indicators. When the CPD reduces and the hake/shrimp ratio increases beyond certain thresholds, INIDEP recommends the closure of the fishery and the CFP approves a closure resolution. The resolutions of the CFP for opening/closing areas have historically directly followed the recommendations made by INIDEP.

The main indicators used in the assessment and management of the fishery are:
1) Monthly average catch per day (CPD) – The effective day of fishing is considered as the unit of effort effectively applied. Landings are equivalent to catches because discarding of shrimp is negligible. Thus, the yield is expressed in terms of kilograms of shrimp caught by fishing day and assumes the CPD as a proxy indicator of the shrimp abundance.

CPD have been used as indicators of the abundance of shrimp in different periods in the history of the shrimp Patagonian fishery. It is calculated based on a representative sample of fishing vessels that have been in the fishery for several years and have no limitations on fishing throughout the range of the Patagonian shrimp stock. When the monthly series spend several months at lower values than the historical annual average minimum obtained (1995), it can be considered in a precautionary manner that it is a period of potential risk of failure of the renewal of the resource available for fishing (recruitment) (Fischbach et al., 2009).

2) Daily captures per unit effort (CPUE) – effective hours of fishing based on onboard logbooks is considered as the unit of effort. The average yields (daily hours trawling) are used to track the resource dynamic throughout the fishing season, and jointly with the CPD is taken into account to determine the opening or closure of the fishing zones.

3) Hake/shrimp ratio – given that the shrimp fishery is closely related to the hake fishery, the amount of hake bycatch thorough the season is used as an indicator to close the shrimp fishery activities in the hake reproductive area. In 2003 INIDEP recommended that the total catch of hake in the shrimp fishery did not exceed the 34,325 t, considered the biologically acceptable threshold. During the period 2000-2013 the annual average hake bycatch was 30,000 t, and since 2008 the biological threshold has not been surpassed (Villarino & Simonazi 2015). The hake/shrimp ratio threshold for closing fishing areas is not clearly defined for decision making.

4) Size frequency of shrimp individuals. The harvest strategy delays the opening of the fishing season until the shrimp recruited in the fishing gear in the national area reach the best individual sizes (Fischbach & Bertuche 2015). The shrimp sizes are classified in six commercial categories (from L1 to L6, from 10-20 to >80 individuals per kilogram respectively) (Fernández & Machi 2015). Categories from L1 to L4 (from 10 to 60 indiv./kg) are over the size at first maturity (Iorio et al. 2000). The indicator CPD10/60 is the CPD for only L1-L4 categories and it is used to delay the opening of the areas. An ongoing historic series of this indicator starts in 1992.

In the shrimp fishery discarding of shrimp is negligible and therefore the catch is considered to be representative of the abundance (Fischbach & Bertuche, 2015). Since 2006 landings have been increasing and in 2015 the total catch reported was 142,846 tons, representing a historical record in the fishery (Ministerio de Agroindustria y Desembarques, 2015). The magnitude of increase in the shrimp abundance registered in recent years does not seem to relate solely to the current harvest strategy nor is it related to increases in effort by fleets. Also in 2014 and 2015 the industrial fleet used new areas where shrimp concentrations were not observed before; northeastern waters in the national area, the San Matias and San Jose Gulfs off the coasts of Chubut and Rio Negro (Fischbach and Bertuche, 2015).

Other indices also show a positive trend. The CPD shows a steady increase from 2005 to 2014 (Fischbach & Bertuche 2015). Bycatch of hake has not exceeded the threshold recommended by INIDEP since 2008 (Villarino & Simonazzi, 2015). Based on scientific surveys done in oceanographicvessels in January at the beginning of the fishing season, in 2014 the bigger size categories of commercial shrimp(L1, L2 and L3) represented15.7% of the total catch, showing an increasing trend from 2007 when it was 7.7% (de la Garza 2014),

The density of eggs and larvae shows the same pattern over the years and suggests that it may be related to the parental stock. This could be the result of declining fish stocks in Patagonia causing a change in ecosystem oriented to invertebrate dominance; in addition to shrimp, the squat lobster Munida gregaria, the southern king crab Lithodes santolla and the shortfin squid Illex argentinus have reached record abundance levels (Moriondo Danovaro, 2015; Fischbach & Bertuche, 2015).

The management strategy of the Patagonian red shrimp has changed since the development of the fishery 30 years ago, based on the better understanding of the spatial-temporal dynamics of the species. The following graph shows the evolution of total shrimp landings from 1989 to 2015 and identifies critical periods of lower abundance (in red circles) and management measures applied in the fishery.

Source data : Ministerio de Agroindustria Argentina

- 1985: the largest shrimp breeding area (Mazaredo in Santa Cruz province) is permanently closed to fishing.
- 1990: the beam trawl vessels began to operate in the fishery.
- Between 1995 and 1997 the minimum abundance levels were registered.
- 1999: establishment of the hake emergency fishing and trawling banned areas and beginning of the spatial-temporal system of closures and openings of fishing areas.
- Although some areas was closed to fishing activities, there was an increase in fishing effort from 2000, both in number of vessels and fishing days, leading to a new period of decline.
- 2003: summer closure to protect the reproductive processes of northern San Jorge Gulf (Chubut)
- 2005: critical shrimp abundance year. The decrease was a result of low recruitment and the previous years of fishing pressure; consequently the fleet could only operate for six months.
- 2006: all fishing activity was banned in the spawning area of Robredo (north of San Jorge Gulf, Chubut).
- 2006-2015: period of increasing landings

Source data : Ministerio de Agroindustria Argentina

The Federal Fisheries Regime established by Law No.24, 922 promulgated in 1997 recognizes the CFP as the body that sets the national fisheries policy, the fisheries research policy and the national fisheries development plans. The CFP sets the maximum allowable catch by species taking into account the maximum sustainable yield, according to data provided by INIDEP. The CFP has a collegial composition with representatives of the coastal provinces and the national state.

There is no management plan for this fishery. The management of the Patagonian shrimp fishery is based on fishery effort restrictions and spatial – temporal closures. There is no quota system, but in 1988 a maximum annual catch limit of 500 t was set for beam trawl operating in San Jorge Gulf and the National area (Resolution No. 1113 SAGPyA). Recently and based on the positive evolution of the fishery and the increasing catches of recent years (from 17,800 to 127,000 tons between 1988 and 2014), the CFP has invalidated this catch limit (Res. 3 24/04/2014).

In 1990 INIDEP observed signs of over-exploitation of hake and from 1998national landings decreased, establishing a fishing emergency in 1999 (DNU Nº189/99 of the National Executive), which remains in force until today. This led to defining a permanent area of total ban for all types of trawling vessels. Since then the opening and closing of limited zones within the closed area of hake to catch shrimp is determined annually by the CFP on the basis of recommendations and surveys results from INIDEP.

The basic management measures in the fishery are the zoning of fishing effort by fleet type and openings and temporary closures according to the resource status and the protection of reproductive and spawning areas. After the management measures taken during the 90s and 2000s and the increasing abundance of shrimp from 2005, no recovery plan is presently necessary.

This fishery does not have a TAC established but is managed under effort control on different areas/periods.

The magnitude of illegal, unreported and unregulated (IUU) fishing is unknown, nevertheless there are no indications that IUU fishing is a real problem.

Information is only available from the industrial fishery; no public information is available about the interactions between the artisanal fleet and endangered, threatened or protected (ETP) species.

A mapping of the benthic communities in San Jorge Gulf has been conducted, to establish preliminary relationships between the benthic system and the spatial distribution of the Patagonian shrimp; a clear correspondence exists between the benthic associations and granulometric characteristics of the substrate which determine two particular areas. The area including the extremes (capes Dos Bahías and Tres Puntas) is characterized by coarse sediments and the associated fauna is mainly colonial. The area consisting of the northern, southern and mouth regions of the gulf is characterized by fine sediments and the representative taxa are mollusks, echinoderms, crustaceans and polychaetes (Roux et al, 1995). In the Northern part of San Jorge Gulf there are unsuitable grounds for trawling that are core reservoirs maintaining species diversity and richness of natural benthic communities (Roux, 2000; 2009).

Specific studies on the impact of the red shrimp fishery on the ocean floor and on the ecosystem have not been developed. The activity of the fleet is mainly over sandy and muddy bottoms. Around 35% of the offshore bottoms are not viable for trawling and a large area for hake conservation is also protected from trawling, covering ~50% of the hake spatial distribution range (CFP, 2009). The San Jorge Gulf also has a marine park for protecting areas of relevant ecosystems and biodiversity.

Under the Patagonian red shrimp fishery strategy there are year-round closed areas and seasonal/spawning closures. Two identified shrimp spawning and recruitment areas are totally protected and closed year-round to any fishing activity: the permanent closed areas of Robredo and Mazaredo.

The “Parque Interjurisdiccional Marino Costero Patagonia Austral” is located in the northern part of the San Jorge Gulf, with an area of approximately 132,124 ha. It includes a marine area and adjacent islands to the southern part (Leones and Arce) and the permanent closed area of Robredo. This Marine Park extends only one nautical mile from the coast and does not cover the fishing areas of northern San Jorge Gulf. The Park promotes sustainable activities compatible with conservation (National Law N° 26.446/09)