Cats love fish, don’t they?

Fish is a common ingredient of pet food for cats, but consumption of this aquatic food was rare in the past. Stable isotope analysis of cat bones from two archaeological sites in Southwest Asia provides insight into the differential access to fish in the Middle Ages.
Cats love fish, don’t they?

An estimated 6% of all fish caught today are used to produce cat food, and cat owners have no doubt noticed how eager their beloved pets are to eat fish offered to them. Yet, although domestic cats take home a wide variety of birds and small mammals, they rarely catch fish, a phenomenon that has also been observed in feral and wild cats. Since cats are opportunistic hunters, consumption of fish and larger mammals that they cannot catch themselves will occur when they live in or close to a human environment where they can more easily access this food. Direct observation of hunting cats or analysis of stomach contents make it possible to reconstruct the diet of modern animals.

Cat eating fish entrails at market in Mumbai, India
Cat eating fish entrails at market in Mumbai, India (Paul Prescott/Alamy)

In archaeology, such dietary studies initially focussed on human bones, but gradually also animals – both wild and domestic – were analysed. Of the carnivores, dogs have so far received the most attention, while cats have only rarely been analysed, mainly because the number of their relatively small bones found in excavations is quite limited. The paucity of cat remains may also be a reason why its domestication history has been much less investigated compared to other popular domestic animals (e.g. dog, horse, livestock). An ongoing EU-funded project, called ‘Felix. Genomes, food and microorganisms in the (pre)history of cat-human interactions’ ( aims to unravel the relationship between humans and cats in the past from different perspectives. For this, we have at our disposal numerous bones, teeth and even some hair and claws from a total of more than 800 individuals dating from more than 10,000 years ago until the 18th and 19th centuries from archaeological sites in Europe, Southwest Asia and North Africa.

To contribute to the 'food history' of cats, we selected bones from two medieval ports in Southwest Asia, Qalhât, in Oman, and Siraf, in southern Iran. A key feature of these sites is that not only numerous cat bones are available for analysis, but tens of thousands of other animal bones have also been studied before. Previous research on food waste made it possible to reconstruct the diet of humans during the Middle Ages, hence what would have been theoretically available for cats to eat or scavenge.

Anastasia Brozou processing bone collagen samples in the stable isotope lab of the Division of Soil and Water Management of the University of Leuven.

Not surprisingly given the coastal position of these sites, a heavy reliance on fish in the human diet was observed. Hence, we were expecting to obtain a very clear signal of fish in the carbon and nitrogen stable isotope results for the cats too. This was indeed the case for the cats from Qalhât that showed a very strong marine signal in the collagen of their bones. In fact, the values are the most elevated ever seen in hundreds of cats that we have so far analysed from other sites in our wide study region. The explanation lies in the fact that fish was no doubt an important part of their diet, but in particular in the fact that the majority of the fish landed at Qalhât were large pelagic species such as tunas and sharks.

Compared to Siraf, the people in Qalhât ate more fish that, moreover, came more from open water (based on frequency counts of the excavated bones).

An archaeologist working at the site told us that at the landing places along the Omani coast fishermen typically gut these large fish and that the entrails attract numerous cats. The medieval cats from Qalhât were likely stray animals that survived by scavenging on fish offal and it appears from the numerous pathologies on their bones that they were not in very good health.

Fishermen gutting sharks and tuna at the sea shore, Oman (Robin Laurance/Alamy)

On the contrary, the cats from the Iranian coastal town of Siraf were apparently in better physical shape, at least no pathological signs were noted on their bones. Although these cats are also from a port, the isotopic results did not show a clear marine signal. Yet fish was a major part of the human diet, albeit less than compared to Qalhât. An additional explanation may be that the fish at Siraf were mainly coastal fish which are lower in the food chain than the pelagic fish that predominate at Qalhât. It also appears from the stable isotope data that the cats from Siraf had frequent access to meat of cattle, sheep and goat, and that beef in particular was an important part of their diet. This is remarkable as the proportion of cattle bones is low in the household refuse of the excavated buildings. However, this does not necessarily mean that beef was rarely consumed as the meat may have been distributed to the consumers without the bone. Moreover, the structures where the cat bones were found are located in the area of the
Great Mosque, in the commercial heart of the urban center where there are numerous shops and where butchers likely also practiced their craft. The presence of such a guild of cattle butchers at Siraf would be not surprising as this large town offered no doubt good sales opportunities. It has been shown in many Roman and Byzantine archaeological sites that artisanal cattle butchers typically produced large accumulations of butchery waste. There is no evidence yet for such dumps at Siraf, but the town was not completely excavated and only 10% of the excavated bones has been analysed so far. It is therefore possible that large accumulations of cattle bones, on which cats may have scavenged, have been missed in the archaozoological surveys. In any case, the results that we obtained from the two medieval port sites showed that cats’ access to fish was very variable despite apparent similar settings. Local conditions, cultural or other attitudes towards these felines may all have played a role in their access to aquatic food. Maybe not all cats that would eat fish would wet their feet?

Group of harbour cats in Bahrain, 2005 (credit: Adele O’Shea)


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