RV Mtafiti’s 17-day research expedition of North Kenya Bank

A Bank off the northern Kenya coast is acquiring significance - the North Kenyan Bank (NKB). With the Kenyan government’s plans to shore up revenue generated from fisheries resources, the fishing zone has been identified as an important emerging fishery that is expected to spur economic growth for the local fishing communities. This is so because artisanal fishers have depleted fish catches in narrow waters and are now advancing towards the North Kenyan Banks which is largely unexploited in search for fish.

Red snappers packed in a cooler box ready for dispatch to the market

Sustainable exploitation of blue resources is the main focus of the Blue Economy initiative aimed at raising the marine fisheries worth from the current Sh2.6 billion. The government is banking on RV Mtafiti vessel to explore the offshore territorial and EEZ waters.

A little is known about this fishing zone. This is what made the Kenya Marine and Fisheries Research Institute (KMFRI) team headed by KMFRI’s Assistant Director Oceanography and Hydrography Dr Joseph Kamau swing into action by dispatching an 18-member team comprised of researchers and technologists onboard the research vessel for the 17-day research expedition at NKB.

 The aim of assessing NKB’s productivity is to inform policy-making and decision-making by relevant institutions in Kenya and enable KMFRI apply herself to the investments of the Blue Economy. The fishery zone is unique along the coastline of tropical East Africa, and is of considerable interest as it holds huge potential likely to boost local fishery resources hence the need to conduct a survey of the area.

Researchers and technologists at work onboard RV Mtafiti

 The cruise that took place from 1st April to 17th April, 2019, was conducted with funding from the Kenya Government through KMFRI and the SOLSTICE-WIO to complement the strategic objective of KMFRI, and also the Kenya National Oceans and Fisheries Policy (2008) objectives. The survey started off at the Southern Coast transect progressing Northwards.

“SOLSTICE is focused on addressing research gaps and provide important information to enhance the NKB fishery management and its sustainable utilisation,” said Dr Kamau.

“SOLSTICE research is aligned to the NKB challenges. The physical and biogeochemical drivers of the high productivity of the NKB including relative importance of the Tana River input and the shelf break and coastal upwelling.”

 Dr Kamau said the RV Mtafiti expedition will be key in assessing economic impacts on Kenya’s fishing communities under climate change and its consequences for its Blue Economy strategy.

 A preview of research equipment deployed during the cruise

During the research cruise, KMFRI researchers deployed a number of sophisticated marine research equipment to collect data. They include grabber, Acoustic Doppler Current Profiler (ADCP), piston corer, CTD rosette, zooplankton and phytoplankton nets, as well as Remotely Operated Vehicles (ROV). Data collected will be disseminated to relevant government agencies to inform investments in the Blue Economy and moreso in the fisheries sector.

ADCP is deployed in deep sea waters at a depth of 300 metres. The equipment is crucial in generating hydro-acoustic data and providing information on water current behaviour, fish biomass and abundance, and helps in characterisation of benthos. ADCP helps in conducting geological survey to study the formation of the North Kenyan Banks, while EK60, a marine research equipment, was used to generate data on fish density and their location, and identification of plankton community and biodiversity.

ROV, a robotic underwater camera, is deployed at a depth of 1000m to capture images of the seabed, to help in the identification of benthos (the flora and fauna found on the bottom, near the seabed or in the bottom sediments of sea or lake) to enable researchers decide on the most ideal investigations to be conducted in a given transect.

Left, Researchers Ms Wanjeri and Ms Ontomwa collect core samples. Right, Remotely Operated Vehicle (Rov)

During the research, sediment samples were collected using piston corer and grabber to determine potential release of nutrients (e.g., phosphorus) back into the water column, and assess trace elements and productivity of the area. Sediment sampling is also used as a tool in the
evaluation of marine pollution and its source.

Piston’s corer main body is constructed of steel and shaped like a dart with welded fins for vertical stability control during free fall.  Clear core liner tubes made of "cellulose acetate butyrate" plastic slide inside the steel coring barrels to retain the sample or be re-used. A core catcher made of stainless steel fingers welded to a ring keep the sample from falling out of the liner during recovery of the corer. A threaded bronze nose cone provides the cutting edge into the sediment.

A CTD rosette or Sonde is an oceanography instrument used to measure the conductivity, water temperature, density, chlorophyll, dissolved oxygen, PH and pressure of seawater to understand how the oceans affect life. Conductivity can be used to determine the salinity.

Senior scientist Dr Kamau prepares CTD before deployment, Right, piston corer being retrieved

The CTD may be incorporated into an array of Niskin bottles referred to as a carousel or rosette. The instrument collects water samples from various depths and KMFRI team collected samples from depths of 1000m after which data was retrieved for further analysis. The samples will be used to investigate marine life in NKB. This information will enable the government to fully exploit fishery resources in the region.

Bongo nets were used for zooplankton sampling and phytoplankton nets to collect phytoplankton samples. The samples will inform biomass (the live weight or the amount of living matter present in the sample). The value obtained will be used to evaluate the secondary productivity and fishery potentials of the NKB.

Left, deployment of bongonet. Right, Limnologist Dr Tsuma Jembe, Oceanographer Mr Athman Salim and Mr Joseph Kilonzi, a technician, collect phytoplankton samples

Analysis of this data will be critical in establishing the health status of the ecosystem and fisheries productivity in the North Kenya Banks and whether there’s an upwelling.

“The Tana River discharges sediments into the Ocean. These sediments from Tana River pileup to form a 130m mountain. It is this mountain of Tana River sediments that are perturbated during the South East Monsoon as the EACC gains its northerly momentum. This causes the seeding of the NKB system with nutrients deposited by the Tana River from the fertile catchment area enhancing productivity and the fishery stocks,” explained KMFRI’s Assistant Director Oceanography and Hydrography Dr Joseph Kamau.

 Recent studies show that the productivity of the North Kenya Bank is deemed to be driven by the Tana River sediments and nutrients input (both dissolved and particulate). Tana River provides high nutrients that flow over the North Kenya Banks at the convergence of the East African Coastal and Somali currents resulting in a highly productive environment. The interaction of the currents and the topographic features of the bank might be the main productivity driver of the system. The shearing of the bank by the EACC and other oceanic currents may cause localised upwelling cells.

 Documentation of Massive Online Open Course (MOOC)

The cruise also paved the way for capturing photos and footages of the research activities onboard RV Mtafiti for an upcoming Massive Online Open Course (MOOC) dubbed “North Kenyan Bank: The Next Frontier for Food Security”. This will be a five-week module MOOC funded by SOLSTICE, aimed at showing how science can be applied to foster Blue economy sustainable growth. It will focus on fishing zones in Ngomeni and Lamu.

Past Surveys of the North Kenya Bank

 Previous studies in North Kenya Banks were carried out by new fishery and oceanographic research vessel RV Dr Fridtjof Nansen which was delivered in January 2017 and launched in May same year. The vessel is equipped for marine research in developing countries in Africa, Asia and Latin America and focuses on ecosystem studies and fisheries research.

If well managed, North Kenya Banks can be a window of opportunities for achieving national development goals including poverty eradication and wealth creation. Moreover, this huge potential is a critical vehicle for the achievement of the Kenya Vision 2030 development plan and food security and nutrition, a key pillar of the Big Four Agenda.

With the Blue Economy initiatives taking centre stage in the Coast region, KMFRI hopes to leverage on its marine research prowess to sustainably develop fisheries resources in the North Kenya Bank and enable formulation of informed management interventions.


Fishermen grapple with myriad of challenges

 With the infrastructure for the marine fisheries sector being quite limited in Ngomeni sub-location, Gongoni location in Magarini constituency, fishermen use very simple gear, and can only fish in near-shore waters, all of which limits their ability to catch enough fish. They do not have HF Radios and satellite phones for communication while fishing in areas without network coverage. Further, they suffer losses due to lack of enough cooler boxes because their catch go bad before sale. Mr Habib Abdir, a captain of one of fishing boats in Ngomeni, said they need fish sounder, GPS, life jackets and new fishing gears to enable them fully exploit the fishery zone.  Fishermen use handline and longline fishing gears to catch red snappers in the NKB, some which were donated by the Kilifi County Government. Other common fish catches popular in NKB include tuna, ray, lobster, prawns, octopus, and sharks. Fishing is Ngomeni’s mainstay with many families living in abject poverty. This has led to increased sex trade where women sell their bodies for fish. Further, pupils abandon school for fishing while children join school late.

Fishermen at Ngomeni landing site

A kilo of fish goes for Sh200, which is too low when compared to the price of fish in the market. Fishermen decried exploitation by agents who buy their catch and sell to big hotels.   

Hassan Alfani, a fisherman, said tunas are harvested from October to mid-December and is unhappy because it no longer fetches a good price. “Prices of tuna have come down by Sh50 per kg,” he said.

Red snappers and yellow fin tuna caught at NKB

Fishermen in the area, however, acknowledged support from KMFRI scientists. “Dr Nina Wambiji has been teaching us on new fishing methods,” a fisherman said.