Subsistence crops grown in the country include matoke (green bananas), which occupy more than a third of the country's farmland, potatoes, beans, sweet potatoes, cassava, wheat and maize. Coffee and tea are the major cash crops for export, with the high altitudes, steep slopes and volcanic soils providing favourable conditions. Reports have established that more than 400,000 Rwandans make their living from coffee plantation. Reliance on agricultural exports makes Rwanda vulnerable to shifts in their prices. Animals raised in Rwanda include cows, goats, sheep, pigs, chicken, and rabbits, with geographical variation in the numbers of each. Production systems are mostly traditional, although there are a few intensive dairy farms around Kigali. Shortages of land and water, insufficient and poor-quality feed, and regular disease epidemics with insufficient veterinary services are major constraints that restrict output. Fishing takes place on the country's lakes, but stocks are very depleted, and live fish are being imported in an attempt to revive the industry.