EOFException при чтении пользовательского класса с помощью ObjectOutputStream

Я столкнулся со следующим EOFException:

java.io.EOFException
at java.io.ObjectInputStream$BlockDataInputStream.peekByte(ObjectInputStream.java:2903)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1502)
at java.io.ObjectInputStream.readObject(ObjectInputStream.java:422)
at Practica.Animalario.Poblacion.abrirPoblacion(Poblacion.java:37)
at InterfazGrafica.Ventana.actionPerformed(Ventana.java:122)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2348)
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
at java.awt.Component.processMouseEvent(Component.java:6533)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3324)
at java.awt.Component.processEvent(Component.java:6298)
at java.awt.Container.processEvent(Container.java:2236)
at java.awt.Component.dispatchEventImpl(Component.java:4889)
at java.awt.Container.dispatchEventImpl(Container.java:2294)
at java.awt.Component.dispatchEvent(Component.java:4711)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4888)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4525)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4466)
at java.awt.Container.dispatchEventImpl(Container.java:2280)
at java.awt.Window.dispatchEventImpl(Window.java:2746)
at java.awt.Component.dispatchEvent(Component.java:4711)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:758)
at java.awt.EventQueue.access$500(EventQueue.java:97)
at java.awt.EventQueue$3.run(EventQueue.java:709)
at java.awt.EventQueue$3.run(EventQueue.java:703)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:80)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:90)
at java.awt.EventQueue$4.run(EventQueue.java:731)
at java.awt.EventQueue$4.run(EventQueue.java:729)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:80)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:728)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)

При выполнении этого кода, который я написал. Цель этого кода — чтение/запись объектов в файл:

public class Poblacion implements Serializable{
    public Raton poblacion [];
    public String nombrePoblacion;
    public String responsable;
    public int dias;

    public Poblacion (){
        poblacion = null;
        nombrePoblacion = "";
        responsable = "";
        dias = 0;
    }

    public Poblacion (String nombre, String cientifico, int _dias){
        poblacion = null;
        nombrePoblacion = nombre;
        responsable = cientifico;     
        dias = _dias;
    }

public class Raton {
    String codigoReferencia;
    Date fechaDeNacimiento;
    int peso;
    String sexo;
    float temperatura;
    String observaciones;
    char X1;
    char X2;
    char Y1;

    public void Raton(String _codigo, Date _fecha, int _peso, String _sexo, float _temp, String _obs, char _x1, char _x2){
        codigoReferencia = _codigo;
        fechaDeNacimiento = _fecha;
        peso = _peso;
        sexo = _sexo;

        if (sexo.equals("Macho")) {
            X1=_x1;
            Y1=_x2;                    
        } else {
            X1=_x1;
            X2=_x2;
        }

        temperatura=_temp;
        observaciones=_obs;       
    }

    public String toString(){
        return codigoReferencia+fechaDeNacimiento+peso+sexo+temperatura+X1+X2+Y1+observaciones;
    }
}



    public static Poblacion abrirPoblacion (File file) throws ClassNotFoundException, IOException {
        File archivo = file;
        FileInputStream fileInputStream = null;
        ObjectInputStream objectInputStream = null;
        Poblacion poblacion=new Poblacion();

        try {
            fileInputStream = new FileInputStream(archivo);
            objectInputStream = new ObjectInputStream(fileInputStream);
            System.out.println(objectInputStream.readObject());
            poblacion = (Poblacion) objectInputStream.readObject();
        } catch(IOException ex) {
            ex.printStackTrace();
        } finally {
            try {
                if (objectInputStream!=null) {
                    objectInputStream.close();
                }
            } catch(IOException ex) {
                ex.printStackTrace();
            }
            try {
                if (fileInputStream!=null) {
                    fileInputStream.close();
                }
            } catch(IOException ex) {
                ex.printStackTrace();
            }
            return poblacion;
        }
    }



    public static void crearPoblacion (String _nombre,String _responsable, int _dias) {
        File archivo = new File("C:\\Users\\rober\\OneDrive - Fundación Universitaria San Pablo CEU\\Java\\Práctica 1"+"\\"+_nombre+".dat");
        FileOutputStream fileOutputStream = null;
        ObjectOutputStream objectOutputStream = null;
        Poblacion nuevaPoblacion = new Poblacion(_nombre,_responsable,_dias);

        try {
            fileOutputStream = new FileOutputStream(archivo);
            objectOutputStream = new ObjectOutputStream(fileOutputStream); 
            objectOutputStream.writeObject(nuevaPoblacion);
        } catch(IOException ex) {
            ex.printStackTrace();
        } finally {
            try {
                if (objectOutputStream != null) {
                    objectOutputStream.close();
                }
            } catch(IOException ex) {
                ex.printStackTrace();
            }

            try {
                if (fileOutputStream != null) {
                    fileOutputStream.close();
                }
            } catch(IOException ex) {
                ex.printStackTrace();
            }
        }
    }