More than 8,000 migrants have reached the Canary Island of El Hierro by boat in five weeks, prompting local authorities to declare a social emergency.

The island has just over 12,000 residents. Nearly 6,000 people arrived in the first ten days of November, mostly on El Hierro. More than 3,000 came in the five days before the declaration on Friday, aboard around 30 small boats called cayucos.

The declaration called for more staff, better first reception facilities and faster transfers. The influx is partly explained by the closure of other migration routes.

Four cayucos carrying 377 people reached La Restinga between Tuesday night and Wednesday morning. The first boat carried 111 people. Passengers said they left Kafountine, Senegal, seven days earlier. Others reported departing M’bour and Saint Louis five to six days before.

The passengers came from Guinea Bissau, Gambia and Mali. Others came from Senegal and Guinea Conakry. Charts from the US National Oceanic and Atmospheric Administration show waves reaching three metres in the waters north of the islands. At least eight people died on the Atlantic route during the first six days of November.

Rescue workers reported getting as little as three hours of rest a day. A rescue vessel was temporarily out of service after running out of fuel. Conditions at the island's hospital became undesirable.

The Red Cross ran out of clothing supplies. A resident named Ángeles said: "Son vidas humanas llegando en una situación muy lamentable, no tenemos ni medios físicos ni efectivos para poder acoger con dignidad a esta gente." She added: "Si nuestro Gobierno, nuestras instituciones y nuestro Cabildo están colapsados, nuestro pueblo está vendido."

45 migrants were transferred to Zaragoza without prior notice. Several had ulcerative wounds and poor health.