1
Harnessing global fisheries to tackle micronutrient deficiencies 1
2
3
4
Christina C. Hicks
1, 2
, Philippa J. Cohen
2,3
, Nicholas A. J. Graham
1,2
, Kirsty L. Nash
4,5
,
5
Edward H. Allison
3,6
,
Coralie D’Lima
3,7
, David J. Mills
2,3
, Matthew Roscher
3
Shakuntala H. 6
Thilsted
3
,
Andrew L. Thorne-Lyman
8
, M. Aaron MacNeil
9
7
8
9
10
1
Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK 11
2
Australian Research Council, Centre of Excellence for Coral Reef Studies, James Cook 12
University, Townsville, Australia 13
3
WorldFish, Jalan Batu Maung, Batu Maung 11960 Bayan Lepas, Penang, Malaysia 14
4
Institute for Marine and Antarctic Studies, University of Tasmania, Private Bag 129, 15
Hobart, TAS 7001, Australia 16
5
Centre for Marine Socio-ecology, University of Tasmania, Hobart, TAS 7000, Australia 17
6
School of Marine and Environmental Affairs, University of Washington, Seattle, 18
Washington 98102 USA 19
7
WWF-India, Goa Science Centre Complex, Mirimar, Panjim, Goa, 403004, India 20
8
Department of International Health, Center for Human Nutrition, Johns Hopkins Bloomberg 21
School of Public Health, Baltimore, MD, USA 22
9
Ocean Frontier Institute, Department of Biology, Dalhousie University, Halifax, Nova Scotia 23
B3H 4R2 Canada 24
*email: christina.hicks@lancaster.ac.uk 25
26
27
2
Micronutrient deficiencies account for an estimated one million premature deaths 28
annually, and for some nations can reduce GDP by up to 11%
1,2
, highlighting the need 29
for food policies focused on improving nutrition rather than simply increasing volumes 30
of food produced
3
. People gain nutrients from a varied diet but fish, a rich source of 31
bioavailable micronutrients essential to human health
4
, are often overlooked. A lack of 32
understanding of the nutritional composition of most fish
5
and how nutrient yields vary 33
among fisheries has hindered policy shifts needed to effectively harness the potential of 34
fisheries for food and nutrition security
6
. Here, using the concentration of seven nutrients 35
in more than 350 species of marine fish, we estimate how environmental and ecological 36
traits predict nutrient content among marine finfish species. We use this predictive model 37
to quantify spatial patterns of nutrient concentration from marine fisheries yields 38
globally and compare nutrient yields to the prevalence of micronutrient deficiencies in 39
human populations. We find that species from tropical thermal regimes contain higher 40
concentrations of calcium, iron, and zinc; smaller species contain higher concentrations 41
of calcium, iron, and omega-3; and, species from cold thermal regimes or those with a 42
pelagic feeding pathway contain higher concentrations of omega-3. There is no 43
relationship between nutrient concentrations and total fisheries yield, highlighting that 44
nutrient quality of a fishery is determined by species composition. For a number of 45
countries where nutrient intakes are inadequte, nutrients available in marine finfish 46
catches exceed the dietary requirements for coastal (within 100km) populations, and a 47
fraction of current landings could be particularly impactful for children under five years. 48
Our analyses show that fish-based food strategies have the potential to substantially 49
contribute to food and nutrition security globally. 50
51
52
3
Uneven progress in tackling malnutrition has kept food and nutrition security high on the 53
development agenda globally
1,3
. Micronutrients, such as iron and zinc, are a particular focus; 54
it is estimated that nearly two billion people lack key micronutrients
7
, underlying nearly half 55
of all deaths in children under the age of five years
1
, and reducing GDP in Africa by estimates 56
of up to 11%
2,3,7
. Consequently, efforts to tackle malnutrition have shifted from a focus on 57
increasing energy and macronutrients (e.g. protein) towards ensuring sufficient consumption 58
of micronutrients
3
. People gain nutrients from a mix of locally produced and imported food 59
products. Fish, harvested widely and traded both domestically and internationally, are a rich 60
source of bioavailable micronutrients, which are often deficient in diets that rely heavily on 61
plant-based sources
6,8
. Fish could therefore help address nutritional deficiencies if there are 62
sufficient quantities of fishery-derived nutrients accessible in places where deficiencies exist. 63
However, addressing this major food policy frontier has been elusive, in part because the 64
nutrient composition of fish varies significantly among species, and data remain sparse for most 65
species
5
. 66
67
Here we determine the contribution marine fisheries can make to addressing micronutrient 68
deficiencies. First, using strict inclusion protocols (methods), we developed a database of 2,267 69
measures of nutritional composition, from 367 fish species, spanning 43 countries, for seven 70
nutrients essential to human health: calcium, iron, selenium, zinc, vitamin A, omega-3 (n-3 71
fatty acids), and protein. We then gathered species-level environmental and ecological traits 72
that capture elements of diet, thermal regime, and energetic demand in fish
9,10
to develop a 73
series of Bayesian hierarchical models that determine drivers of nutrient content (Methods). 74
75
4
Our models successfully predicted nutrient concentrations, with posterior predictive 76
distributions consistently capturing both the observed overall mean and individual values of 77
each nutrient
11
(Extended Data Figs. 1 and 2; Methods). We found that calcium, iron, and zinc 78
– nutrients critical in preventing public health conditions such as stunting and anaemia
7,12
– 79
were in higher concentrations in tropical fishes (Fig. 1). Tropical soils are often zinc and 80
calcium deficient because these nutrients are easily exported from land to sea during strong 81
pulse rainfall events common in the tropics; this process may elevate levels of these nutrients 82
in marine food-webs
13
. Higher concentrations of calcium, zinc and omega-3 were found in 83
small fish species. Small fish consumption is promoted, particularly in Asia and Africa
14,15,
as 84
a rich source of micronutrients and, although these high concentrations are often linked to the 85
practice of consuming fish whole
15
, we also detected elevated levels of these nutrients in 86
muscle tissue. 87
88
Greater concentrations of omega-3 – which supports neurological function and cardiovascular 89
health
16
– was found in species that are pelagic feeders, are from cold regions, and approach 90
their maximum size more slowly (Fig. 1). Pelagic feeders consume plankton, the main source 91
of omega-3 in aquatic systems
17
, whereas species adapted to a colder thermal regime, have a 92
greater need for energy storage compounds and fat, including fatty acids
18
. Selenium 93
concentrations were higher for species found at greater depths and lower for species in tropical 94
waters, whereas lower concentrations of vitamin A were found in species from cold regions, 95
with high trophic levels and short, deep body shapes. Concentrations of protein were greater in 96
higher trophic level species, and those with a pelagic feeding pathway, and lower in species 97
found in cold regions, and with a flat or elongated body shape (Fig. 1). 98
99
5
Given the alignment between our posterior predictions and observed data (Extended Data Fig. 100
2), we used our trait-based models of nutrient concentration, and traits for species within the 101
landed catch of the world’s marine fisheries
19
, to produce the first global estimates for 102
nutritional concentration (Fig. 2) and nutritional yield (Extended Data Fig. 3) of marine 103
fisheries (Methods). These data reflect catches from within a country’s Economic Exclusive 104
Zone (EEZ) that are landed and consumed domestically, landed outside the country by foreign 105
fleets, or traded internationally
19
. We include both officially recorded and reconstructed 106
unrecorded catches (see Methods for comparisons), but do not include discards. There was no 107
correlation between the concentration of nutrients per unit catch and either total nutrient yield 108
or total fishery yield (Extended Data Fig. 4), suggesting the nutrient quality of fishery landings 109
is influenced by species composition rather than the quantity landed; and thus, fish-based food 110
policy guidelines
e.g. 20
should specify for what types of fish consumption is advised. 111
112
High concentrations of iron and zinc (>2.5mg 100
-1
g and >1.8 mg 100
-1
g respectively, of raw, 113
edible portion) are found in the species caught in a number of African and Asian countries (Fig. 114
2, Extended Data Table 1), the same regions at greatest risk of deficiencies in these nutrients
7,12
. 115
This suggests that, in areas of critical public health concern, a single portion (100g) of an 116
average fish provides approximately half the recommended dietary allowance (RDA) of iron 117
and zinc for a child under the age of five years. Calcium concentrations are high (>200mg/100g 118
raw, edible portion) in the species caught in the Caribbean region, an area with a high 119
prevalence of deficiency risk
7
, again highlighting the potential contributions fish can make to 120
targeted health interventions in these areas. Concentrations of selenium and omega-3 are high 121
(>25ug 100
-1
g, >0.5g 100
-1
g respectively, of raw, edible portion) in fish species caught from 122
high latitude regions including parts of Russia, Canada, Northern Europe, and Alaska (Fig. 2, 123
Extended Data Table 1). This is consistent with omega-3 observed as abundant in marine foods 124