In order to evaluate the state of the physical environment several sources of information are used. Area surveys of temperature and salinity are conducted in January-February during the joint winter survey, and in August-October during the joint ecosystem survey. The standard sections also form an important base to evaluate temperature and salinity. In particular, seasonal changes are monitored at the Kola and Fugløya-Bear Island sections, and at the fixed station in Ingøy.
In the Fugløya-Bear Island section, a series of current meter monitors provide high resolution flow measurements through the western entrance of the Barents Sea. In addition, hydrodynamic numeric models provide insight into horizontal and vertical temperature variation, water masses distribution, and water transport. Satellite data also provide sea surface temperature, salinity, ice cover measurements.
Figure 3.3.1 and 3.3.2 indicate months during which phytoplankton species and cell numbers were sampled by Norwegian ships at the Fulgløya-Bjørnøya (FB) and Vardø-Nord (VN) transects, and the spread (within these months) of sampling date during the period 2004-2012. For operational reasons, sampling time and effort are not entirely uniform in all years, which limit the ability to detect changes in species composition and diversity over time; this is particularly important during spring and summer. Combined with the considerable patchiness in distribution of phytoplankton, and occurrence of mono-specific “blooms” this makes detection of any changes in species composition very difficult during the short time period for which data are available.
Figure 3.3.x1: Sampling times and effort for the period 2004-2013 for the VN transect.
Figure 3.3.x2: As for Figure 3.3.x1, but for the FB transect.
These surveys measure chlorophyll concentration at standard depths down to 100 m. Species composition and abundance have been determined since 2005 from water samples. Murmansk Marine Biological Institute (MMBI) conducts cruises in eastern regions of the Barents Sea, sampling chlorophyll, and phytoplankton species composition and abundance at standard depths. In addition, color satellite data indicate phytoplankton bloom dynamics.
Zooplankton biomass and species distribution are monitored during the joint autumn ecosystem survey. Joint Russian and Norwegian zooplankton investigations have taken place since 2002. Regular sampling by IMR began in 1979 while PINRO has conducted these surveys since 1982 up to 1993. A Juday net (37 cm in diameter, 180 μm) is used to obtain zooplankton samples by PINRO. IMR uses a WP2 net (56 cm in diameter, 180 μm) and a 1 m2 MOCNESS multiple plankton trawl with 9 nets all having a mesh size 180 μm, as standard zooplankton gears. The MOCNESS is mainly used for obtain better data on the vertical distribution of mesozooplankton and the gear is also somewhat more efficient with regard to the larger zooplankton components like arrow worms, euphausiids and hyperiids. However, for some years now the Norwegian Macroplankton trawl has been used in predetermined regions of Norwegian sector of the Barents Sea. Sampling approach has been to conduct double oblique hauls, from surface to near the bottom both on RV G.O. Sars and RV Johan Hjort. The aim has been to obtain integrated samples of macroplankton like euphausiids and hyperiids for improved assessment of their population structure. The Macroplankton trawl is a fine-meshed plankton trawl having an approximate 38 m2 mouth-opening and 3 mm stretched meshes from the trawl-opening to the rear end (see Melle et al. 2006, Wenneck et al. 2008, Krafft et al. 2010, Heino et al. 2011). Towing speed is normally 2.5–3 knots.
In 2005 comparisons were made between the Juday and WP2 net catches from the joint autumn cruises both with regard to biomass and species composition. The biomasses obtained by the two gears are quite similar. A report on the comparisons of the two gears was prepared at a joint meeting held at IMR in May 2006 and the EcoNorth symposium in Tromsø in March 2007. During the Ecosystem survey in August-September 2007 a specially designed double-net system, holding side by-side one Norwegian WP2 net and one Russian Juday net, was used to sample the water column at selected stations in order to compare the sampling efficiency of the two nets for various mesozooplankton components. A total of 19 hauls were conducted with the double-net system. Samples have been worked up for biomass comparisons, and a special workshop was arranged in Bergen 22-26 October 2007 where most of the samples were analyzed for species composition and abundance by Russian and Norwegian specialists. All double-net hauls were operated with a vertical speed of 0.5 m s-1 from RV G.O. Sars. The analyses from this work are in due progress and will be reported at a later stage. During the Ecosystem Survey in 2013 an additional set of data from the WP2/Juday dual net system was obtained. This time a total of 40 WP2+Juday dual net hauls were conducted on 19-20 August 2013, half of them during night and the others during daytime. One aim of this exercise was to compare gear sampling performance when haul retrieval speed was increased from 0.5 to 1 m s-1. Preliminary results from the initial gear comparison totalling 19 hauls have already been obtained, but with the new 2013 data a more thorough analysis of the dual-net comparisons can be completed.
Monitoring of mesozooplankton along the Fugløya-Bear Island section by IMR started in 1987 and are now conducted 5-6 times each year usually in January, March/April, May/June, July/August and September/October. In addition the Vardø-N section and its extended part are currently sampled 2 times a year (March/April and August/September). However, data prior to 1994 are scarce and does not give a full seasonal coverage. The WP2 plankton net has been used regularly during this monitoring since 1987. In addition vertically stratified MOCNESS tows are taken during the two-month Ecosystem survey in August-September each year, approximately one haul pr. day.
Monitoring of mesozooplankton along the Kola Meridian transect was conducted by PINRO in 1959-1993 during ichthyoplankton survey. In 2008 such sampling was resumed and mesozooplankton is sampled once a year (at the end of May-early June) in three layers 0-50 m, 50-100 m and 100 m-to the bottom. Juday net is used as the main sampling gear.
Regular macroplankton surveys have been conducted by PINRO in the Barents Sea since 1952. Surveys involve annual monitoring of the total abundance and distribution of euphausiids in autumn-winter trawl-acoustic survey. To collect macroplankton a net attached to trawl (so-called “trawl net”) (0.2 m2 opening area, 564-µm mesh size) was used. This net is a modification of egg net IKS-80 and it is attached to the headline of a bottom trawl and catch plankton near the bottom. During winter, crustaceans are concentrated in the near-bottom layer and have no pronounced daily migrations, and the consumption by fish is minimal. Therefore sampling of euphausiids during autumn-winter survey is used to estimate year-to year dynamics in their abundance in the Barents Sea. Annually 200-300 samples of macroplankton are collected during this survey, and both species and size composition of euphausiids are determined. It is necessary to note that in spite of quite a large mesh size, the net can catch both small and large animals (Orlova et al., 2004a, b).
Gelatinous zooplankton (ctenophores and cnidarians) are caught in both the WP2 net and the MOCNESS plankton trawl. However, it is questionable to which degree catches can be considered truly quantitative especially for the larger ctenophores and scyphozoans. In addition many species are damaged in nets. Thus their actual abundance can be severely biased. Since larger cnidarians of the class Scyphozoa are also caught in the pelagic Harstad trawl used for 0-group fish and capelin we have chosen in this report to present catches from this trawl, although caution should be exercised in their quantitative interpretation.
Yearly monitoring of shrimps and the benthos community is conducted during autumn as part of the Joint Ecosystem Survey. This benthic mapping survey was initiated by PINRO in the early 1930’s, continued in the 1960’s, and then resumed in 2000. In addition to long-term monitoring programmes in the Barents Sea, basic mapping of the benthic organisms and habitat is carried out by the MAREANO project, which also maps shelf areas of the Barents Sea; plans are to expand mapping from the southern Barents Sea northward within the Norwegian zone.
Since 1982, annual trawl surveys have been conducted to gather information on shrimp stock biomass and demographic composition for the assessment. From 2004, the ecosystem survey was expanded to also include king crab, snow crab, and all other benthic species caught in the trawl.
Analysing the Campelen trawl invertebrate by-catch is a time and cost effective method that was easily implemented in the Joint Ecosystem Survey. Since 2005, Russian and Norwegian benthic scientists have developed routines to secure standardised methods on both Russian and Norwegian ships (Chap 4.3.3). These methods require further development, and need to be verified with quantitative benthic sampling tools to validate the Campelen trawl as a benthic sampling tool.
In addition to collecting data on red king crabs during from the Joint Ecosystem Survey, joint red king crab monitoring surveys have been carried out in the southern coastal Barents Sea each year. Information on king crab stock size and life stages is collected during these surveys. These surveys also provide the main data source for stock assessment
The snow crab population has had a large increase in recent years. A monitoring programme for this species is under development.
To ensure a method that follows benthic fluctuations in the Barents Sea, long-term monitoring areas have been established. These areas were selected using criteria such as time and cost effectiveness, human impacts, natural variation, and geographical variation (Table 3.3.1).
Table 3.3.1. Monitoring areas in the Barents Sea for monitoring of the changes in benthos under influences of different anthropogenic and environmental factors.
Benthic monitoring on Shtokman field and the Kola section has been carried out by MMBI. For the Kola section, the data time series dates back to 1930s. On the Shtokman field, monitoring has been conducted since 2002.
Most of the surveys mentioned above have monitoring commercial fish species as their main objective. Different fish stocks at different life stages are targeted during these surveys. In addition to catch data, these surveys are the main data source for stock assessments. Data on non-target fish species (abundance, weight, length distribution, etc.) have also been collected during these surveys over the last ten years.
Additional sources of information include biological data collected by Russian observers’ onboard commercial fishing vessels, and a number of commercial fishing vessels with special reporting demands serving as reference vessels.
Most marine mammal monitoring taking place in the Barents Sea is focussed on either commercially important species or threatened species.
Various methods are used for abundance estimation, which is the normal means of assessing status of mammals. Mark-recapture experiments were used for determining the abundance of harp seals in the 1980s and 1990s (e.g. Øien and Øritsland, 1995), but more recently, the preferred method for estimating abundance of ice-breeding seals and pelagic cetaceans has become strip transect-surveys or “distance” methods using observations from aircraft for seals and ships for whales (Øritsland and Øien 1995; Haug et al. 2006; ICES 2008, ICES 2013). The International Convention for Exploration of the Seas (ICES) requires that quotas for marine mammal species commercially be based on estimates that are less than 5-years old, so this period determines the frequency of monitoring for harvested species. The first aerial surveys of harp seals in the White Sea were conducted in 1927-1928 at the time of moulting (Shafikov, 2008). Pup production estimated have been made using surveys flown during the breeding season in the White Sea in 1998, 2000, 2002, 2003, 2004, 2005, 2008 and 2009, 2010 (Potelov et al. 2003; ICES 2013; ICES, 2014), and moulting surveys of harp seals have been flown in 2001, 2002 and 2004 (Chernook et al., 2008).
Hooded seals that breed in the West Ice have received little monitoring attention, despite considerable levels of harvesting following the World War II. The first successful aerial survey for hooded seals took place in 1997, but this was not repeated until 2005 (Salberg et al. 2008, ICES 2008). The low numbers observed in this survey stimulated a repeated surveys in 2007, which showed a similar result as the 2005 survey. The most recent survey was conducted in 2012 and showed a further reduction in pup production albeit not statistically significant (Øigård et al., 2012). and 2008.
Regular sighting vessel surveys, conducted by the Institute of Marine Research, target minke whales and other large baleen whales. The main objective of these surveys is to monitor the northeast Atlantic minke whale population as a basis for setting quotas for the Norwegian minke whale hunt. . These cruises sighting surveys are conducted annually, such that abundance estimates can be calculated for the overall region approximately every 6 years (see Skaug et al. 2004, Solvang et al. 2015). Additionally, the distribution patterns of marine mammals in the Barents Sea have been observed from research vessels during the ecosystem survey (see description of this survey above). In addition aircraft observations and observations from fishing and coastguard vessels with observers are used to explore the temporal and geographic distribution of some marine mammal species.
Aerial photographic surveys are conducted within the national ecosystem monitoring programme - Monitoring of Svalbard and Jan Mayen (MOSJ) to determine the abundance of polar bears (10 year interval – Aars et al. 2009) and walruses (5 year interval – Lydersen et al. 2008, Kovacs et al. 2014). A polar bear survey was flown in the Norwegian Territories in late summer 2015, the results of which will be available early in 2016. Other marine mammals species are also surveyed opportunistically, including ringed seals (Krafft et al. 2006) and harbour seals (Merkel et al. 2013), when research funding permits. Starting in 2002 marine mammal sightings reported from scientific field parties, Coastguard and tourist operators in the Svalbard region are documented on an annual basis.
On the coast of mainland Norway, harbour and grey seals are monitored every 5 years (Nilssen and Haug 2007; Nilssen et al. 2009). For grey seals, population monitoring is based on boat surveys of pup production and total abundance is calculated based on a population model (Øigård et al., 2012). Monitoring of harbour seal abundance is based on aerial surveys of moulting harbour seals (Nilssen et al. 2010).
Overall goals of the seabird monitoring program are to evaluate the status and trends of seabird populations in relation to anthropogenic and natural environmental factors (Anker-Nilssen et al. 1996). Species and sites monitored on Russian and Norwegian sides are summarised in Table 3.3.2. A map showing location of the monitoring sites can be seen on the Russian-Norwegian Barentsportal here.
The seabird monitoring programme for Svalbard was initiated in 1988 (Mehlum & Bakken 1994) and nine species are now (2015) included in the programme: northern fulmar, common eider, northern gannet Morus bassanus, great skua Catharacta skua, glaucous gull Larus hyperboreus, black-legged kittiwake, common guillemot, Brünnich’s guillemot and little auk (Strøm 2006). Monitoring of population development is carried out annually for all nine species except little auk. Data on survival, breeding success and chick diet are monitored on Bjørnøya for all species except northern fulmar and gannet; on Spitsbergen for black-legged kittiwake, Brünnich’s guillemot, glaucous gulls and little auk (Strøm 2006). The seabird monitoring programme in Svalbard is organized by the Norwegian Polar Institute, and data stored in the institute’s Seabird Colony Database – COLONY (Bakken 2000).
The national monitoring programme for seabirds on the Norwegian Mainland, established in 1988 and revised in 1996, addresses population changes in 18 species of breeding seabirds along the coast, including the three key species (Atlantic puffin, black-legged kittiwake and common guillemot) and six key sites (Runde, Sklinna, Røst, Anda, Hjelmsøya and Hornøya) (Røv et al. 1984, Anker-Nilssen et al. 1996, Lorentsen et al. 2009).
In 2005, the SEAPOP programme (www.seapop.no) was launched. Its aim is to coordinate a long-term, comprehensive, standardised and cost-effective study of the most important aspects of seabird numbers, distribution, demography and ecology in Norway, Svalbard and adjacent sea areas (Anker-Nilssen et al. 2005).The formerly established monitoring activities, which include the national programmes on the mainland and Svalbard and long-term studies of seabird ecology on Røst, Hornøya and Bjørnøya are integrated parts of the SEAPOP programme. SEAPOP thus integrates all previous seabird monitoring activity into one programme (Anker-Nilssen et al. 2005a). The activities in the two initial years were restricted to the Lofoten and Barents Sea area (including Svalbard), but from 2008 the programme was implemented on the full national scale. The work is organised and carried out by the Norwegian Institute for Nature Research (NINA) and the Norwegian Polar Institute (NP) in close cooperation with Tromsø University Museum.
Table 3.3.2. Seabird species and sites monitored in the Barents Sea Region.
There is no national program for monitoring of seabirds in Russia. Extensive seabird studies were initiated in the Russian part of the Barents Sea in the 1920-1930s and systematic studies on seabirds were started in 1938 in the Seven Islands archipelago (eastern Murman coast) at the same time as the archipelago was protected as a strict nature reserve. It also included two of the largest seabird colonies on Novaya Zemlya, Gribovaya and Bezymyannya Bays on the Southern Island, in 1947–1951. Since then seabird monitoring in Russia has been based on a network of strict nature reserves (zapovedniks; IUCN category I). Only selected colonies situated within the boundaries of such specially protected areas are monitored routinely. The longest monitoring series are within the territory of Kandalaksha State Nature Reserve (KSNR; including former Seven Island reserve). Monitoring in this reserve is concentrated in three areas including Kandalaksha Bay (White Sea) and West and East Murman areas (south Barents Sea coast). For some species regular monitoring started in KSNR as early as the late 1920s, resulting in a nearly 80-year time series for some sites.
Monitored species include European shag Phalacracorax aristotelis, great cormorant Phalacracorax carbo, common Uria aalge and Brunnich’s guillemots U. lomvia, black guillemot Cepphus grylle, Atlantic puffin Fratercula arctica, black-legged kittiwake Rissa tridactyla, herring Larus argentatus, great black-backed Larus marinus and mew Larus canus gulls, arctic skua Stercorarius parasiticus, arctic tern Sterna paradisea and common eider Somateria mollissima. Long-term monitoring data from the Murman coast was reviewed by Krasnov et al. (1995). Unfortunately, the monitoring program in the remote areas on the Barents Sea coast was closed down for some years due to staff shortage and logistic problems in the KSNR, but has later resumed. Monitoring has continued in the Kandalaksha Bay (total counts since 1970s) but now with reduced coverage. In addition to population numbers, monitoring parameters include productivity, diet and phenology.
Since 1999, several new monitoring sites have been established on the southern Barents Sea coast as a scientific initiative by the Murmansk Marine Biological Institute Russian Academy of Science (MMBI RAS). Monitoring efforts are concentrated on the Kola Peninsula both in the breeding colonies and on the inshore nonbreeding grounds. Monitoring of seabird breeding populations was established in 2000 in three sites in Western Murman (Gorodetsky Cape, since 2000) and Eastern Murman (Krutik Cape, since 2003).
Monitoring of chemical contamination in the environment and in marine resources in the Barents Sea was initiated by PINRO in 1986. The importance of conducting pollution monitoring on a systematic and regular basis has become more evident after exploration drilling started in the 1990s. Different institutions take part in the regular monitoring.
Among them are:
- The institute of marine research (IMR) monitors radioactive elements, oil hydrocarbons and various organic chlorinated and brominated compounds in fish, seawater and sediments
- Norwegian Radiation Protection Auhority (NRPA) monitors radioactive elements in seaweed
- Norwegian Geological Survey (NGU) monitors inorganic substances like heavy metals in sediments
- Norwegian Institute of Nutrition and Seafood Research (NIFES) monitors various organic and inorganic pollutants in seafood (fish and shrimps)
- On assignment for Norwegian Environment Agency, Norwegian Institute of Water Research (NIVA) monitors inorganic and organic pollutants in sediments, fish (cod) and shellfish from coastal areas and riverine inputs to the area
- Norwegian Polar Institute (NPI) monitors various types of pollutants in marine mammals (polar bear, ringed seal) and birds (Brünnich guillemot)
- On assignment for Norwegian Environment Agency, Norwegian institute for air research (NILU) monitors atmospheric pollution at the Zeppelin station on Svalbard
- The MMBI –biomonitoring and determination of chemical elements and compounds in sediments and the water column through its own network of stations
- PINRO – monitors annualy, heavy metals, n-alkanes, PAHs and OC (PCB and pesticides) are measured in sediments, sea water (surface and bottom water) and fish samples (cod, haddock, saithe, capelin, long-rough dab)
- VSEGEI –monitoring of the geological environment in the Kola Bay (annually)
- Sevmorgeo – monitoring of the geological environment in the coastal zone of the Kola Peninsula – 1 time in 1-2 years
In addition to regular monitoring, the national program of geochemical, geological, and biological mapping of the seabed, the MAREANO project has, since 2006, provided detailed information on levels of certain organic and inorganic pollutants. Institutions taking part in MAREANO seabed monitoring are IMR and NGU. In 2013, NGU and SEVMORGEO jointly prepared a lithological map of the Barents Sea, which provides a basis for hydrobiological and geochemical constructions; it is currently posted on the Norwegian Geological Survey and MARIANO websites. Other Norwegian institutions also contribute to measuring contaminant levels in the Barents Sea through screening programmes, scientific projects, etc.
Further, geo-environmental work, including compilation of geochemical and geoecological maps, is part of geological mapping of scale 1:1000000 (MAGE and VNIIOkeangeologiya).
Types of pollutants and monitoring frequency are summarised in Table x.1, and monitoring stations for fish and sediment samples for 2005-2008 are given in Figures x.2 and x.3.
Figure 3.3.3. NGUs sediment sampling stations of the 2003-2006.
Figure 3.3.4 Sediment sampling stations of the 2005-2008 PINRO cruises.
Figure 3.3.5 Fish sampling stations of the 2005-2008 PINRO cruises.
Figure 3.3.6 NIFES sampling stations for Polar cod, cod, shrimp and capelin 2008 and earlier.
Figure 3.3.7 Sevmorgeo sampling stations in 2014 in the Teriberka Bay/Type of sampling:
Table 3.3.3. Pollutants monitored by Norwegian and Russian institutions in the Barents Sea and periodicity of monitoring.
Table 3.3.3. Pollutants monitored by Norwegian and Russian institutions in the Barents Sea and periodicity of monitoring - continue.
Monitoring total fishery removals is an essential component of an ecosystem approach to sustainably manage the exploitation of marine systems. Effective fisheries monitoring is a valuable tool to: enforce fishery regulations and adherence to catch quotas; evaluate the effectiveness of management strategies; and provide data needed for stock assessments. In addition, effective fisheries management should include long-term catch monitoring data needed to assess the effects of fishing on the ecosystem (NMFS 1999). Fisheries monitoring programs are also useful to evaluate whether management actions are protecting fished stocks and the communities and habitats these stocks depend upon (Bonzek, 2006).
Quota and technical monitoring
Fisheries regulations are enforced at sea, when the catch is landed, and when it is exported. At sea, the Coast Guard is responsible for inspecting fishing vessels and checking the catch against the vessel’s log books. Norwegian, Russian, and other countries’ fishing vessels are subject to stringent controls. Monitoring by the Coast Guard is generally considered vital to functioning of the management regime as a whole. In Norway the Directorate of Fisheries also inspects vessel activities on the fishing grounds.
Vessels over 15 meters are required to carry satellite transponders which make it possible to track their activity 24 hours a day throughout the year. When catch is landed, landings data for individual vessels are checked against their fishing rights and vessel quotas. In Norway, the Directorate also performs physical inspections of landings at landing sites. When irregularities are detected — at sea, at landing sites, or through subsequent controls — serious cases are referred to the courts.
Controlling fishing activity on fish stocks shared internationally requires close cooperation between the affected states. In 1975, Norway and Soviet Union established the Joint Norwegian–Soviet (Russian now) Fisheries Commission, and in 1976 a framework agreement was signed on mutual fisheries regulation. The Joint Norwegian–Russian Fisheries Commission, and its subcommittees, meets regularly to discuss and decide on management issues, including technical measures. There is a common understanding that protection of juveniles is an essential part of responsible management; criteria and procedures for real time area closures are jointly agreed upon. Both parties have restrictions on discarding in their legislation.
To improve exploitation patterns and reduce discards, Norway and Russia have established a suite of regulations and management measures. The primary objective is to promote an exploitation pattern that reduces fishing mortality of individual fish below a minimum legal size, and minimizes unwanted bycatch. This has been achieved through several interconnected measures, which Gullestad et al. (2015) refers to as the “Discard Ban Package”.
Most current fish stock assessment models require input data on catch (biomass), fish size (length), and fish age. In the Barents Sea, detailed catch data exist for most fleets and important commercial fish stocks; in some cases data are incomplete. Fisheries for commercial species in the Barents Sea — cod, haddock, saithe, Greenland halibut, golden redfish (Sebastes norvegicus), deep-sea redfish (S. mentella), and others — exhibit spatial differences in catch composition and catch size. Also, there are large differences in patterns of exploitation between countries.
Typically only data from the industry (landings reports, and vessel logbooks) are used to make estimates of retained catch. However, there are examples where clear evidence of underreporting has required use of additional sources of information. Estimates of unreported catch of cod and haddock during 2002-2008 indicate that this has been a serious problem. Even if underreporting now seems to be less of a problem, continuous control and surveillance of this is necessary. Although discarding — of cod, haddock, saithe, and a number of other species, — is illegal both in Norway and Russia, it still is believed to be significant during certain periods. Data on discards are scarce, but attempts to obtain better quantitative reporting are ongoing.
PINRO conducts biological sampling of size and age composition of commercial catches through a program of onboard observers on fishing vessels. During 2013, biological samples were collected from 20 fishing vessels a total of 1034 days-at-sea in all areas fished by the Russian bottom trawl fleet. Some waters within Russian and Norwegian EEZs were not covered. In Norway, there is no onboard-observer program similar to that in Russia. The Norwegian data collection program consists of port sampling by staff from the Institute of Marine Research or individuals contracted locally, self-sampling by the Norwegian Reference Fleet (a contracted sub-sample of the entire commercial Norwegian fleet), the Coast Guard upon inspection at sea, and the Directorate of Fisheries which may deploy on-board observers/inspectors during fishing vessels.
The Joint Norwegian-Russian Fisheries Commission (JNRFC) has defined common conversion factors to convert the weights of different cod and haddock products to live (round) weights for all nations fishing for these species in Subareas I and II. These conversion factors have hitherto been fixed throughout the year, and for all sizes of cod and haddock. However, results from recent joint field studies should provide more precise conversion factors.
Analyses to estimate total catch are performed by stock-responsible assessment scientists / technicians at IMR and PINRO. However, there is no single method used to combine these various data sources — vessel log books, landings reports — to estimate total catch. This relates to the fact that landings reports are considered precise regarding catch (biomass) by species, but not as precise regarding catch location. Vessels log books are more precise regarding catch location, but less precise regarding biomass. Therefore, these data sets are combined to obtain as accurate estimates of biomass per location and season as possible. Vessel log book data are also used when constructing catch-per-unit-effort (CPUE) series, either to tune data series in analytical assessments or as self-standing indicators of changes in stock biomass. VMS data are not used routinely to estimate total catch, but are used when a higher geographical resolution is required for logbook data or a more precise measure of effort, e.g., splitting redfish catch by species (Sebastes norvegicus or S. mentella) based on depth.
The salient question is how well do these fisheries monitoring programs characterize total fisheries removals that results in acceptably precise estimates of fish stock size and setting appropriate levels of Total Allowable Catch (TAC). Regular evaluations to answer this question should be a central component of any fisheries monitoring program. The Estimating Catch-at-age (ECA) model — a modeling framework to estimate catch-at-age of commercially harvested fish species — can be used to estimate numbers of fish caught within each age group for shared stocks (Hirst et al., 2012 The model can be applied to Russian and Norwegian data to assess the precision of total catch and catch-at-age, and provide input data to assessment models. This will help determine the precision of assessment results used to support management advice. Plans are to apply the ECA model to both Russian and Norwegian catch sampling data to support assessment methods development.