Duration: up to sixteen (16) months

Modality: remote consultancy, with travels

Estimated level of effort: Up to 45 working days (indicative)

Maximum budget: EUR 39,999 (VAT excl.), including mission fees (travel + per diem)

1. Objectives of the assignment

The assignment falls under the project “Sustainable Western Indian Ocean Programme – Subcomponent 1.2” (“SWIOP 1.2”) implemented by Expertise France in support to two Regional Fisheries Management Organisations (RFMO), including the IOTC, and contributes to the project’s objective of strengthening the scientific basis for RFMO decision-making. The consultant will support selected activities related to CPUE standardisation, the integration of priority fisheries into IOTC analytical work, and the review and testing of data-limited assessment approaches for neritic tuna species.

The consultancy will cover three complementary areas of work: CPUE standardisation for the Seychelles longline fishery, CPUE-related analysis for Comoros tuna fisheries, and the review and testing of data-limited assessment approaches for IOTC neritic tuna species. Together, these tasks aim to strengthen the evidence base available to IOTC where fisheries data are either under-used, insufficiently standardised, or too limited to support conventional stock assessment approaches.

2. Scope of the assignment

2.1. Task 1 - CPUE for Seychelles longline fishery

The Seychelles industrial longline fleet consists of large, long-distance vessels that operate both on the high seas and within the Seychelles EEZ, where they primarily target bigeye tuna and yellowfin tuna. Compared to the main DWLN fleets, the Seychelles industrial longline fleet has a shorter history and smaller geographic coverage, but maintains reasonably consistent fishing patterns and targeting strategies, providing an important additional source of information. Seychelles vessels are obligated to submit logbooks wherever they operate for the entire duration of the registration period. The logbook data covers the years from 2000 to the present and captures information for individual fishing sets. Key variables include trip/set code, vessel ID, location, setting time, number of hooks, and catch in both numbers and weight by species. Positions by latitude and longitude are usually recorded with high precision. The data are thoroughly verified, validated, and maintained by the Seychelles Fishing Authority (SFA). SFA has agreed to provide the IOTC Secretariat access to this dataset in accordance with the data confidentiality policy and procedures as per IOTC Resolution 12/02 

In 2025, the IOTC Secretariat collaborated with SFA through a consultancy to provide a preliminary evaluation and analysis of the Seychelles longline data, focusing on internal consistency and offering several recommendations on the filtering and processing of length, catch, and effort data for stock assessment purposes. The current consultancy will build on those results and leverage the strong working relationship between the IOTC Secretariat and SFA to work towards CPUE standardisation of longline fishing data from the Seychelles fleet (The IOTC Secretariat will coordinate with SFA on accessing the logbook dataset for the analysis, along with outputs from the previous work). This represents important capacity-building work and fits well within the Scientific Programme of Work, specifically the SWIOP projects that include capacity-building on CPUE indices and stock assessment.

The consultant shall specifically follow the below-detailed methodology:

•    Collaborate with the Seychelles Fishing Authority (SFA) to further assess the quality of operational-level catch/size data from their longline vessels. This serves to provide a robust criterion for filtering data for CPUE standardisation and future stock assessments. This step shall build on the outputs of the previous analysis as described in IOTC-2025-WPTT27-28, and focus on data components submitted to the IOTC Secretariat.
•    Collaborate with the SFA to develop standardized CPUE indices for the longline fleet on a species-specific level, using an appropriate mathematical or statistical model that can account for various sources of variability in the observed catch rates. These should initially be focused on the key tuna species (bigeye tuna, yellowfin tuna, albacore tuna where feasible and appropriate).
•    Provide technical training to SFA staff on the standardisation procedure and help them become familiar with the scripts so they can reproduce and update the analysis independently in the future.

The consultant is expected to travel to Seychelles to work with SFA on the standardisation analysis for approximately five days (excluding days on travel). The dates are to be confirmed with SFA/IOTC Secretariat and are expected to be in August or September 2026.

2.2. Task 2 -  CPUE for Comoros Tuna Fishery

As part of ongoing capacity development activities, Comoros was identified as one of the CPCs with limited data processing capabilities. In 2026, the IOTC Secretariat conducted a capacity development mission to assess the availability of fishery data and the data processing systems in Comoros. In Comoros, the sampling of key species at major landing sites has been implemented through a programme established in 2011. A database system was developed to store and manage the collected data, which remains the primary data management system in Comoros and continues to be well maintained. In more recent years, Comoros has further enhanced data collection through digital tools, and an estimation procedure was developed within the database application to improve annual catch estimates by species and fishery based on sampled data. At present, samplers collect data using a mobile application, with data stored on a cloud-based server. The main types of fisheries in Comoros include small non-motorised paddle boats, medium-sized vessels equipped with outboard engines, and larger vessels with outboard engines primarily targeting non-tuna species. The main fishing gears used for targeting tuna and tuna-like species include handlines, troll lines, and longlines.  The main segment of fisheries to be analysed in this consultancy are the small and medium-sized vessels that target tuna and tuna-like species.

The consultant should specifically follow the below-detailed methodology:

•    Fishery characterization analysis: Collaborate with the DGRH (Direction Générale des Ressources Halieutiques) of Comoros, with support from the IOTC Secretariat, to analyze and characterize the catch, effort, and species composition data for tuna fisheries collected through the landing site sampling program.
•    Data suitability assessment: Assess the quality of the catch, effort, and species composition data from Comoros, and ascertain whether a suitable fishery component (handline, trolling, or longline) can be identified for which a consistent subset of data exists to permit standardization analysis.
•    CPUE analysis: Pending the conclusions of the data suitability assessment, develop standardised CPUE indices at a species-specific level if a suitable fishery component or data subset can be identified. These should initially focus on the key tuna species (bigeye, yellowfin, and albacore) and fisheries where feasible and appropriate.
•    Technical training: If the CPUE analysis is conducted, provide technical training to DGRH staff on the standardization procedure and help them become familiar with the scripts so they can reproduce and update the analysis independently in the future.

The consultant is expected to travel to Comoros to work with DGRH on the analysis for a maximum of 10 days (excluding travel days). The dates are to be confirmed with DGRH /IOTC Secretariat and are expected to be sometime between February and April 2027. The IOTC Secretariat will coordinate with DGRH on accessing the data for the analysis. The number of days may be reduced if the data suitability assessment indicates that the CPUE analysis is not feasible.

 2.3. Review of development of data-poor stock assessment methodologies for IOTC neritic tuna species

Within the IOTC area of competence, coastal and semi-pelagic fisheries targeting neritic tunas represent an important component of national catches and domestic seafood supply. These fisheries are mainly conducted by small-scale fleets operating in coastal waters, where data on catch composition, effort and biological data remain scarce. Neritic tuna stocks are difficult to assess. The stock structure remains uncertain. The species are widely distributed but mixing appears to be local, meaning it is difficult to develop ocean-wide index of abundance that is often essential for the assessment. There is often a lack of robust data collection systems such as logbook. National sampling programs provide limited coverage of the fisheries, and data quality are difficult to assess. Regional studies on fish biology such as growth and maturity are inconsistent, exhibiting large variability in parameter estimates across regions. The IOTC Scientific Committee and its Working Parties on Neritic Tunas have repeatedly highlighted the need for interim analytical approaches capable of supporting management decisions even in the absence of complete datasets

IOTC has been using a range of data-limited stock assessment methods for assessing neritic tuna species. These methods use partial datasets such as total catches, length-frequency samples or qualitative indicators of abundance to estimate the relative stock status. Unlike traditional models that require detailed time series of catch and effort, data-poor approaches rely on simple relationships between biological traits such as growth rate, lifespan and maturity, and observed catch trends to approximate stock productivity and fishing pressure. Commonly applied tools include Catch-MSY, which estimates the range of sustainable yields compatible with observed catches, Length-Based SPR (LB-SPR), which uses size composition data to infer fishing mortality and spawning potential, and Depletion-Based Stock Reduction Analysis (DB-SRA), which estimates stock biomass trajectories under uncertainty. These methods require very limited data input, are easy to implement and interpret, and can produce estimates of reference points that are useful for management advice. However, the caveats with these approaches are well known. The catch-only method requires catch data to be complete and accurate, which is unlikely to be the case for some neritic tuna species. The length methods require representative data from the fishery, but key assumptions such as stationary recruitment and asymptotic selectivity are often not met. Depletion-Based methods often require strong prior assumptions on depletion level through the course of the fishery history, which can be subjective and can directly drive the outcome of the assessment. These caveats can add uncertainty to the assessment and may hinder the adoption of effective management measures
 
Management Strategy Evaluation (MSE) approaches have also been suggested and discussed at IOTC Working Party for Neritic tuna. Through a simulation framework, the MSE aims to provide harvest control rule or management options that are robust to a wide range of uncertainty, and as such are suitable for species for which there is considerable uncertainty regarding stock structure, population dynamics, and status. For example, an operating model conditioned on catch, size frequency, and possibly some index would be suitable for assessing the status of neritic tuna and providing advice that is commensurate with the data. The MSE projects populations under different fishing intensities to test index-based HCR and/or justify risk-based reference points and decisions, and could be a pragmatic approach to implement reasonable and precautionary decision-making in fisheries management. One option under this route is to create automated software that is much simpler to use and can be plugged directly into the existing DLM stock assessment software such as JABBA and Fishblicc. This approach can be a bridge between simple assessments and full MSE, and can be a useful add-on to current approaches if it improves robustness.

To respond to this challenge, the consultant is required to support the testing and adaptation of data-limited or “data-poor” assessment methods. The task includes conducting a review of the current assessment methodologies, developing a prototype workflow to explore the potential extension of the current data-limited methods, including the use of a “MSE-lite” approach (i.e., not a full-fledged MSE) to derive simple harvest control rules and reference quantities through simulations. 

Specifically, the consultancy shall implement the following task:

•    Review the current stock assessment approaches for IOTC neritic tuna species (with priority on longtail tuna, kawakawa, and Spanish Mackerel), including the availability, gaps, and quality of data and their suitability for the assessing the stock status. Review the assessment methodology including the potential bias, and major sources of uncertainty that needs to be addressed. Review the current management quantities and advice and comment on whether they have been adequately supported by the assessment.
•    Investigate potential extension and adaptation of current methods, including the use of simulation-based approaches to recommend risk-based reference points or evaluate simple harvest control rules for precautionary management and adequately address the inherent uncertainty, using one neritic tuna species as a case study.

3.  Explicit exclusions from the assignment

To avoid any ambiguity of roles, the consultant shall not:

•    Represent Expertise France or IOTC vis-à-vis the European Union, partner institutions, States or stakeholders;
•    Coordinate, supervise or manage project activities or teams;
•    Assume decision-making, validation or arbitration authority;
•    Manage budgets, contracts, procurement or administrative processes;
•    Substitute for the Project Coordinator or any member of the Project Management Unit.

All recommendations provided by the consultant will be non-binding and subject to validation by Expertise France and IOTC. 

4. Expected deliverables 

The consultancy will be structured around a limited number of clearly identified deliverable categories, with an indicative level of effort (LoE) and an indicative delivery timeline, to be confirmed and adjusted at the beginning of the service. 

The table below presents the expected main deliverables, their estimated workload and indicative timing, for an overall ceiling of up to 45 working days over a maximum period of sixteen (16) months.

All deliverables shall be submitted in English and in editable format. Analytical scripts, code, configuration files and related outputs shall be provided in reusable and sufficiently documented formats. Technical deliverables will be reviewed by the IOTC Secretariat, with Expertise France ensuring contractual follow-up and formal validation in accordance with the contract.