Integrated seaweed – sea cucumber farming in Tanzania

Andreas Kunzmann,Flower E Msuya,Marisol Beltran-Gutierrez,Mary Namukose,Godfrey Fabiani

doi:10.4314/wiojms.v17i2.4

Andreas Kunzmann, Flower E Msuya + Show 3 more

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https://doi.org/10.4314/wiojms.v17i2.4

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Abstract

We review piloted co-culture experiments of the sea cucumber Holothuria scabra with different seaweed species in existing lagoon-based seaweed farms in Tanzania during 2011-2014. Key questions were whether stocking densities would influence growth rates of both species, and whether deposit feeders would modify organic components in the sediments. From a social perspective, we investigate if local people are readily willing to become involved in sea cucumber farming as an optional livelihood. Seaweed-specific growth rates between 0.32 and 4.1 %d −1 were reported, showing significantly higher values for those treatments combined with sea cucumbers than for the seaweed monocul - ture (F 3,1 =3.20, p<0.05) at Zanzibar sites. Sea cucumber growth rates ranged from 0.14 to 1.6 gd -1 , and all of the studies showed that the treatments holding H. scabra at a low stocking density (average of 130 gm -2 ) presented a higher growth performance than when it was stocked at more than 200 gm -2 . Total organic matter in sediments increased in all treat- ments over the sampling periods (p<0.05). Some 88 percent of the surveyed local people showed willingness to partici- pate in this type of mariculture for livelihood. The survey identified theft and lack of credit as the main hindrances for this activity. H. scabra is viable for lagoon co-culture with seaweed when taking into account proper stocking density, implications on total organic matter and total organic carbon in the system, and local acceptance by local people.

Highlights

Seaweed is important for Tanzania, both from social, ecological and economic points of view
H. scabra is viable for lagoon co-culture with seaweed when taking into account proper stocking density, implications on total organic matter and total organic carbon in the system, and local acceptance by local people
Growth rates of seaweed and sea cucumbers Seaweed growth rates In Muungoni, Zanzibar, mean initial K. striatus density of 570gm-2 increased to 1.600gm-2 after one culture cycle of 41 days, reaching a specific growth rate (SGR) of 4.1%d−1. This was the highest seaweed growth registered in the trial studies, which was recorded in co-culture with sea cucumbers at low stocking density

Summary

Introduction

Seaweed is important for Tanzania, both from social, ecological and economic points of view. The direct use of seaweeds for human consumption worldwide is in the range of 300 000 tons/year with species such as Nori (Porphyra spp.), Ulva, Fucus and others being produced (CEVA, 2013). About 10–12 million tons/ year of seaweed are harvested from the wild and from aquaculture, and some used in the seaweed processing industry (Nayar and Bott, 2014) with a value of US$ 6 billion. In Tanzania about 11-15 thousand tons (dry weight) of Eucheuma and Kappaphycus species are produced yearly, with a total value of 1.6 – 2.0 billion Tsh (Msuya, 2012; Msuya et al, 2014)

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